Answer Key
Level 3 Algebra Placement Test Study Answers
-
University:
Santa Ana College -
Course:
MATH 280 | Intermediate Calculus Academic year:
2019
-
Views:
422
Pages:
18
Author:
omiliar74be
Level 3
1
INTERMEDIATE ALGEBRA READINESS DIAGNOSTIC TEST PRACTICE
Directions: Study the examples, work the problems, then check your answers at the end of each topic. If
you don’t get the answer given, check your work and look for mistakes. If you have trouble, ask a math
teacher or someone else who understands this topic.
TOPIC 1: ELEMENTARY OPERATIONS
A. Algebraic operations, grouping, evaluation:
To evaluate an expression, first calculate the
powers, then multiply and divide in order from
left to right, and finally add and subtract in order
from left to right. Parentheses have preference.
example:
example:
example:
example:
14 − 3 = 14 − 9 = 5
2 • 4 + 3• 5 = 8 + 15 = 23
10 − 2 • 32 = 10 − 2 • 9 = 10 −18 = −8
(10 − 2) • 32 = 8 • 9 = 72
2
23.
24.
25.
26.
27.
3+ 6
=
3+ 9
6axy
=
15by
2
19a
=
95a
14 x − 7y
=
7y
5a + b
5a + c
23 =
−24 =
4 + 2•5 =
32 − 2 • 3 + 1 =
5. 0 =
4
6. (− 2) =
5
7. 1 =
example:
4
Problems 8-13: Find the value if a = − 3 , b = 2 ,
c = 0, d = 1, and e = − 3 :
8. a − e =
11.
9. e + (d − ab)c =
12.
2
10. a − (bc − d) + e = 13.
+ −
=
=
b
a
2d
e
x 2 − (x − x 2 ) =
3
4
Problems 21-32: Reduce:
22.
•
x (x−4 )
2x − 6
(ab )
c
bc
c
= ac • bc
=
ac
bc
35. 2 3 • 2 4 = 2 x
3
36. 24 = 2 x
40. 8 = 2
41. a x = a 3 • a
37. 3−4 =
42.
2
3
=5
52
52
=
1
3x
x
( ) =2
39. 2
4 3
x
43.
x
44.
b 10
b5
1
c −4
= bx
= cx
a 3 y− 2
a 2 y− 3
= ax
Problems 45-59: Simplify:
45. 8x =
0
50. (−3) − 3 =
3
3
46. 3 =
47. 2 3 • 2 4 =
51. 2 x • 4 x −1 =
c+ 3
52. 2 c−3 =
48. 0 =
0
49. 5 =
53. 2 c + 3 • 2 c − 3 =
x
54. 8x−1 =
−4
5
26
65
x 2 −3x
x− 4
Problems 35-44: Find x:
38.
=
= • = 1• = 4
example:
(note that you must be able to find a common
factor - in this case 9 - in both the top and
bottom in order to reduce a fraction.)
a
= 33aa••41b = 33aa • 41b = 1 • 41b = 41b
example: 123ab
(common factor: 3a)
=
34.
0
18. 3a − 2(4(a − 2b) − 3a ) =
19. 3(a + b) − 2(a − b) =
10r − 5(2r − 3y) = 20. 1+ x − 2x + 3x − 4 x =
13
52
=
VI. a = 1 (if a ≠ 0 )
VII. a− b = 1b
a
2
B. Simplifying fractional expressions:
21.
(ab)
IV.
V.
2
3
4
• 10x
=
y2
b c
6x + 3 − x − 7 =
2(3 − t) =
9
9
3•10• x • y
15•x•y 2
y
3 5 2 x
• • • • •1=
3 5 1 x y y
1 • 1 • 2 • 1 • 1 • 1y = 2y
3
•y
x 15
=
III. (a ) = a
Problems 14-20: Simplify:
9• 3
9• 4
2x 2 −x−1
x 2 −2x+1
I. a b • a c = a b + c
b
II. aa c = a b − c
=
= 3x − x + y − 2y = 2x − y
2
2
example: a − a + a = 2a − a
27
36
32.
=
C. Laws of integer exponents:
example: 3x + y 2 − (x + 2y 2 )
14.
15.
16.
17.
31.
• yxy2 • 3y2 =
4x
6
Combine like terms when possible:
2
30.
x−4
=
4−x
2( x + 4 )(x − 5)
( x−5)(x−4 )
x 2 −9x
=
x− 9
8( x−1) 2
=
6( x 2 −1)
Problems 33-34: Simplify:
33.
e
d
b
e
d
c
29.
=
Problems 1-7: Find the value:
1.
2.
3.
4.
28.
2
2
= 55.
−3
2x
6 x −4
(
58. − 2a
=
( )=
56. a
57.
x +3 x
3 x− 2
a
a 2 x− 3
59.
2
) (ab )=
2(4 xy ) (−2x y )
2 4
2
2 −1
example:
2
−1
=
=
Problems 67-74: Write answer in scientific notation:
−2
40
example: 32800 = 3.2800 ×10 if the zeros in
the ten’s and one’s places are significant. If
4
the one’s zero is not, write 3.280 ×10 ; if
4
neither is significant: 3.28 ×10
−3
example: .004031 = 4.031× 10
2
example: 2 × 10 = 200
−1
example: 9.9 × 10 = .99
n
Problems 60-63: Write in scientific notation:
69.
1.86×10 4
3×10 −1
=
73.
70.
3.6×10 −5
1.8×10 −8
=
74.
76.
To compute with numbers written in scientific form,
separate the parts, compute, and then recombine.
)
3.14 ×10 5 (2) = (3.14 ) (2) ×10 5
= 6.28 ×10
4.28×10 6 = 4.28 ×
−2
2.14
5
2.14 ×10
10 6
10 −2
Answers:
1. 8
2. –16
3. 14
4. 4
5. 0
6. 16
7. 1
8. 0
9. 9
10. –5
11. –3
12. − 2 3
13. no value (undefined)
14. 5 x − 4
15. 6 − 2t
16. 15 y
2
17. 2 x − x
18. a + 16b
19. a + 5b
20. 1 − 2 x
2
1
2
4
5
3
4
2ax
5b
a
5
2x − y
y
5a + b
5a +c
27.
28. -1
2(x + 4 )
29. x − 4
30. x
4 (x −1)
31. 3(x +1)
32.
33.
34.
35.
36.
37.
−1
(−2.92×10 )(4.1×10 )
3
−8.2×10 −3
a
a
7
=
=
77. 3 + −3 =
78. 3 − −3 =
Problems 79-84: If x = −4 , find:
79. x + 1 =
80. 1 − x =
81. − x =
82. x + x =
83. −3 x =
84. ( x − ( x − x ) ) =
= 2.00 ×10 8
21.
22.
23.
24.
25.
26.
2
example: 3 = 3
example: −3 = 3
example: a depends on a
if a ≥ 0 , a = a
75. 0 =
−6
66. 4 × 10 =
(
=
Problems 75-78: Find the value:
Problems 64-66: Write in standard notation:
3
( )=
(2.5 ×10 ) =
72. 4 ×10−3
10 −40
10 −10
if a < 0 , a = −a
example: − −3 = −3
62. 5.07 =
63. −32 =
64. 1.4030 × 10 =
−2
65. −9.11×10 =
=
E. Absolute value:
Note that scientific form always looks like a ×10
where 1 ≤ a < 10 , and n is an integer power of 10.
60. 93,000,000 =
61. .000042 =
1.8×10 −8
3.6×10 −5
71.
68.
4
example:
= .250 ×10 3 = 2.50 ×10 2
67. 10 ×10 =
D. Scientific notation:
example:
2.01×10 −3
8.04 ×10 −6
2x +1
x−1
2
x2
x
2
7
–1
4
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
0
12
3
4
5
4
y +1
8
1
81
128
0
1
–54
2 3x −2
64
4c
2 2x +1
x
3 3
x 2 + 3x
66.
67.
68.
69.
70.
71.
72.
73.
74.
75.
56. a
x +1
57. a
9 2
58. 16a b
2
59. x 3
60.
61.
62.
63.
64.
65.
9.3 ×10 7
4.2 ×10−5
5.07
–3.2 × 10
1403.0
-.0911
76. 1 if a > 0;
-1 if a < 0;
(no value if a = 0 )
77. 6
78. 0
79. 3
80. 5
81. –4
82. 0
83. 12
84. 12
.000004
38
1× 10
1× 10−30
6.2 × 104
2.0 × 103
5.0 × 10−4
1.6 × 10−5
4.0 ×10−3
1.46 × 1013
0
TOPIC 2: RATIONAL EXPRESSIONS
A. Adding and subtracting fractions:
If denominators are the same, combine the
numerators:
example:
3x
y
− xy =
3x − x
y
=
2.
3.
4
7
+ 27 =
3
− x −x 3 =
x−3
b−a
− ab +− ba =
b+a
4.
example:
example:
5.
6
b
= 5 ab ; 56a = bb • 56a = 56ab
5a
3x+2
= 4 (x+1) ; 3xx ++12 = 44 • 3xx ++12
x+1
x−1
= (x+1)(x−2) ;
x+1
(x−2)(x−1)
x−1
x 2 −3x+2
= (x−2)(x+1) = (x+1
x+1
)(x−2)
7.
8.
4
= 72
9
3x
= 7y
7
x+3
= (x−1)(x+2)
x+2
2
3( x+2)
+8
= 12x
4 x+4
9.
10.
2
3( x +2)
=
ax
6(x +1)
=
How to get the lowest common denominator
(LCD) by finding the least common multiple
(LCM) of all denominators:
example: 5 6 and 8 15 .
First find LCM of 6 and 15:
6 = 2• 3
15 = 3• 5
LCM = 2 • 3• 5 = 30
5
8
= 16
so, 6 = 25
, and 15
30
30
1
6a :
and
ax
6( x +1)
2•2(x +1)
2•3(x +1)(x +2)
ax (x +2)
6(x +1)(x +2)
4 (x +1)
= 6(x +1)(x +2) and
Problems 11-16: Find equivalent fractions with
the lowest common denominator:
12.
2
3
3
x
and 5
13.
x
3
and
11.
and
2
9
14.
15.
−4
x +1
16.
3
x−2
and
4
2− x
7x (y−1)
x
and 10(x−1)
15(x 2 −2)
2
1 3x
, , and x x2 + x
x x +1
After finding equivalent fractions with common
denominators, proceed as before (combine numerators):
− a4 = 24a − a4 =
example: x −31 + x +1 2
example:
30−15a
= (1+b )(1−b )
15−15b
x −6
= −2
6− x
and
3(x + 2) = 3 • (x + 2)
6(x + 1) = 2 • 3 • (x + 1)
LCM = 2 • 3 • (x + 1) • (x + 2)
so,
Problems 6-10: Complete:
6.
example:
4
4 = 2•2
6a = 2 • 3• a
LCM = 2 • 2 • 3• a = 12a
9a
2
so, 43 = 12a
, and 6a1 = 12a
3y 2
x +2
−
=
2
x +2 x
xy 2
3a
+ b2 − ab =
b
If denominators are different, find equivalent
fractions with common denominators:
example: 3 4 is equivalent to how many eighths?
3
= 8 ; 43 = 1 • 43 = 22 • 43 = 22••43 = 68
4
example:
3
2x
y
Problems 1-5: Find the sum or difference as
indicated (reduce if possible):
1.
example:
a
2
3(x +2)
2a− a
4
=
a
4
(x −1)
= (x −1)(x +2) + (x −1)(x +2)
−1
= (3xx−1+ 6)(+xx+2
= 4 x+5
) (x −1)(x +2)
Problems 17-30: Find the sum or difference:
17.
18.
19.
20.
21.
22.
− 21a =
− a2 =
− 2x =
+2=
−2=
a − bc =
3
a
3
x
4
5
2
5
a
b
23.
24.
25.
26.
27.
+ b1 =
a − a1 =
x
+ 1−x x =
x −1
3x − 2
− x +2 2 =
x−2
2 x −1
− 2xx−−21 =
x +1
1
a 4
28. (x −1)(x −2) + (x −2)(x −3) − (x −3)(x −1) =
1
1
29.
4
− x 2 −2
=
x
x
x −2
7
7•6
= 2 1
= 42 = 42 1 = 42
1
− 2 (3 − 2 )• 6 4−3
5x
5x
• 2y 5x
2y
5x
example: 2y ÷ 2x =
= 2y
=
= 5
2x 2x • 2y 4 xy 4 y
2
39. 43 ÷ 23 =
47. 3 =
2
x
−
30. x −2
4
x 2 −4
example:
=
B. Multiplying fractions:
Multiply the top numbers, multiply the bottom
numbers, and reduce if possible.
3 2
• =
4 5
3(x+1)
•
x−2
example:
example:
31.
32.
2 3
•
3 8
a
b
6
20
= 103
x 2 −4
x 2 −1
=
33.
• dc =
34.
(a+b )
(x−y ) ( p−5)
35.
• (5− p) •
(x−y ) 2
(a+b )2
36.
37.
3( x+1)(x+2)( x−2)
= (x−2)(x+1)(x−1) =
3
()
3 2
4
2
( )
3
2a
5b
40. 11 83 ÷
3x+6
x−1
=
38. 2
1 2
2
=
=
C. Dividing fractions:
Make a compound fraction and then multiply the top
and bottom (of the big fraction) by the LCD of both:
example:
a
b
÷ dc =
a
b
c
d
=
a
b
c
d
• bd
=
• bd
Answers:
1. 6 7
2. –1
3. 2b−2a
b +a
4. − 2 x
5. 2ab+2
6. 32
7. 3xy
2
8. x + 2 x − 3
9. 2 + 2b − a − ab
10. 2
11. 69 , 29
12.
13.
14.
3
, 5xx
x
x (x +1)
3(x +1)
,
22.
23.
27.
16.
17.
18.
2
x +1
, 3x
x (x +1) x (x +1)
5
2a
3a−2x
ax
x −4
−3(2x−1)
(x +1)(x−2)
28. 0
29. x +2
x
30.
2
31.
32.
2
33.
( )
15.
,
30(x −2)(x−1)
30(x −2)(x−1)
2
4 x−10
5x
12
5
a−2b
b
ab−c
b
a +b
ab
a 2 −1
a
24.
25. 0
2
26. 3x 2 +2x
3
, −4
x−2 x−2
21x (y−1) x 2 −2
, x(xx +1)
=
48.
3
4
÷2=
49.
42.
a
b
÷3=
50.
43.
3
a
÷ b3 =
51.
44.
x+7
x 2 −9
1
x−3
=
a−4
=
3
−2
a
2a − b
46.
=
1
45.
4
2
3
4
a
b
c
a
=
=
=
b
c
1
− b1
a
=
1
+ b1
a
1
− b1
2a
=
1
1
−
a
2b
1
1
−
a
b
=
1
ab
52.
53.
2
19.
20.
21.
−12
3(x +1)
2x (x−1)
ad
bc
3
4
41.
=
( )
=
3
2
• ab =
7a 12
3(x+4 )
5y 3
•
5y
x 2 −16
2
3
34.
35.
x 2 +2x−4
x 2 −4
1
4
ac
bd
b
42
2
3y
x−4
(a +b )(5− p )
x−y
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
9
16
8a 9
125b 3
25
4
9
8
91
6
3
8
a
3b
9
ab
x +7
x +3
a 2 −4 a
3−2a
46. 4a − 2b
47. 8 3
48. 1 6
49. bca
50.
51.
52.
ac
b
b−a
b +a
b−2a
2b−a
53. b − a 5
TOPIC 3: EXPONENTS and RADICALS
A. Definitions of powers and roots:
Problems 1-20: Find the value:
Problems 44-47: Write given two ways:
Given
No negative No
powers
fraction
d −4
44. 4
1. 2 =
11.
2. 3 =
12.
−125 =
52 =
3. − 4 =
13.
(−5)
4. (− 4) =
14.
x2 =
46.
5. 0 =
4
6. 1 =
15.
16.
a3 =
1
=
4
47.
3
2
2
2
4
7.
8.
3
64 =
17.
64 =
18.
9. 6 64 =
10. − 49 =
19.
20.
3
2
3
=
4
4
=
a b • a c = a b +c
ab
ac
=a
III.
(a ) = a
IV.
(ab)
()
a c
b
V.
IV.
= ac • bc
=
=5
52
52
( )
3 4
25. 2
26. 8 = 2
27. a 3 • a = a x
x
28.
29.
= 2x
30.
b 10
b5
1
c −4
= cx
55.
a 3 y −2
a 2 y −3
38. 2 • 4
c +3
39. x c−3 =
33. 2 3 • 2 4 =
40.
34. 0 =
41.
35. 5 =
36. (− 3) − 3 =
37. x
c+3
•x
3
c− 3
=
x −1
( )
43.
=
x +3 x − 3
3 x −2
a
a 2 x −3
s r
b
1
r
r
a
( ) = (a )
1
1
s
r
1
1
r
s
51. x 2 =
1
52. 2 x 2 =
1
53. (2x ) 2 =
=
3
5=
23 =
56.
3
a=
=
1
a
57.
58.
4• 9= x
61.
59.
x=
62. x =
3
60.
x
8x
=
2 x −1
−3
2x
=
6 x −4
42. a
3
a=
r s
a
r
Problems 58-62: Find x:
= ax
31. 7x =
−4
32. 3 =
0
, or (a b ) r =
1
1
Problems 54-57: Write as a fractional power:
54.
x
5
a
b
48. 3 2 =
2
49. 4 3 =
1
50. (1 2) 3 =
= bx
Problems 31-43: Find the value:
0
a=
r
1
Problems 21-30: Find x:
24.
rs
=
1
1
Problems 48-53: Write as a radical:
a
1
3x
x
r a
b
r
or a rs = a
VI. a = 1 (if a ≠ 0 )
VII. a− b = 1b
23. 3−4 =
p
r
1
c
a
bc
( a)
ab = r a • r b , or ( ab) r = a r • b
r
1
0
21. 2 3 • 2 4 = 2 x
3
22. 224 = 2 x
x 2 y 3 z −1
x 5 y −6 z −3
which is a
real number. (Also true if r is a positive odd
integer and a < 0 )
p
power
Think of r as root
III.
bc
c
3
a 2 bc
2 ab 2 c
p
II.
b−c
b c
−2
3x 3
y
a ≥ 0 , then a r = r a p =
81a 8 =
7• 7 =
B. Laws of integer exponents:
I.
II.
( )
( )
45.
C. Laws of rational exponents, and radicals:
Assume all radicals are real numbers:
I. If r is a positive integer, p is an integer, and
.04 =
(23 )
d
4
9
3
64 = x
8
4
2
3
3
2
64 = x
Problems 63-64: Write with positive exponents:
(
63. 9x 6 y −2
=
)
1
2
=
(
64. −8a 6b−12
D. Simplification of radicals:
example:
example:
3
32 = 16 • 2 = 4 2
72 = 3 8 • 3 9 = 23 9
)
− 23
= 6
54 + 4 16 =
27 • 3 2 + 4 3 8 • 3 2 =
33 2 + 4 • 2 3 2 =
33 2 + 8 3 2 = 113 2
example: 8 − 2 = 2 2 − 2 = 2
example:
3
3
81.
3
example:
65. − 81 =
73. x 2x + 2 2x +
50 =
67. 3 12 =
68. 3 54 =
69. 52 =
74.
3
2x 2
2x
71.
x5 =
79.
a2 =
a3 =
3 5
a =
3 2+ 2=
5 3− 3=
9x2 − 9y2 =
72.
4x6 =
80.
9x2 + 9y 2 =
75.
76.
77.
70. 2 3 + 27 − 75 = 78.
Answers:
1. 8
2. 9
3. –16
4. 16
5. 0
6. 1
7. 8
8. 4
9. 2
10. –7
11. –5
12. 5
13. 5
14. x if x ≥ 0
–x if x < 0
15. a
16. 1 2
17. 0.2
18. 16 81
2
19. 3a
20. 7
21. 7
22. –1
23. 4
24. 0
25. 12
26. 3
27. 4
28. 5
29. 4
30. y + 1
31. 7
2
82.
64 (x + y ) =
3
3
E. Rationalization of denominators:
example:
Problems 65-82: Simplify (assume all radicals
are real numbers):
66.
9(x + y ) =
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
example:
=
46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
56.
57.
58.
59.
=
5
8
=
5
8
•
Problems 83-91: Simplify:
83.
84.
85.
86.
87.
1
128
0
1
–54
x
2 3x −2
x6
2 2x +1
= 9−1 x −6 y 2
9x 6
a3
= 8−1 a 3 b−3
8b 3
y 9z 2
−3 9 2
=x y z
x3
3
3
16
3 1
2
=3
4
2
x =x x
2 x
2x
1
52
3
22
1
a3
−1
a 2
36
3
4
9
1
=
5
3
=
3
a
=
b
3 2 =
3
2+
88.
89.
90.
91.
64.
3
x 2 −9
d
y2
=
63.
2c
x
2
3
1
2
3
=
2 +1
3
=
1− 3
3+ 2
=
3− 2
60. 4
61. 2
62. 1 2
81
42. a
x +1
43. a
44. 18 = d −8
45.
2
= 10 = 410
2
16
1 = 1 •3 4 = 3 4 = 3 4
3
3
3
2
2
2 3 4
8
3
3
3 +1
+ 3
=
•
= 93−1
= 3+2 3
3 −1
3 −1
3 +1
5
8
65.
66.
67.
68.
69.
70.
71.
72.
3x 3
y
b8
4a4
–9
5 2
6 3
33 2
2 13
0
x2 x
3
2x
73. 4 x 2x
74. a if a ≥ 0,
-a if a < 0
75. a a
3
76. a a 2
77. 4 2
78. 4 3
79. 3 x 2 − y 2
80. 3 x 2 + y 2
81. 3 x + y
82. 4 (x + y )
83.
84.
85.
6
5
3
5
3
= 7
86.
87.
ab
3
18
3 2
88.
2
89. 3 2 − 3
b
3
90.
3 +3
−2
91. −7 − 4 3
TOPIC 4: LINEAR EQUATIONS and INEQUALITIES
A. Solving one linear equation in one variable:
Add or subtract the same value on each side of
the equation, or multiply or divide each side by
the same value, with the goal of placing the
variable alone on one side. If there are one or
more fractions, it may be desirable to eliminate
them by multiplying both sides by the common
denominator. If the equation is a proportion,
you may wish to cross-multiply.
Problems 1-15: Solve:
9. x − 4 = x2 + 1
1. 2 x = 9
2. 3 = 65x
3. 3x + 7 = 6
4. x3 = 45
10. 23xx+1 = 52
11. 6 − 4 x = x
12. 32xx−+21 = 4
6. x =
x+3
2 x −1
=2
14. 7 x − 5 = 2 x + 10
15. 13 = x +x 8
5. 5 − x = 9
13.
+1
7. 4 x − 6 = x
8. xx +−11 = 67
2x
5
To solve a linear equation for one variable in
terms of the other, do the same as above:
example: Solve for F: C =
5
9
(F − 32)
= F − 32
+ 32 = F
Add 32:
Thus,
F = 95 C + 32
example: Solve for b: a + b = 90
Subtract a: b = 90 − a
Multiply by
9
:
5
9
C
5
9
C
5
Problems 16-21: Solve for the indicated variable
in terms of the other(s):
16. a + b = 180; b = 19. y = 3x − 2; x =
17. 2a + 2b =180; b = 20. y = 4 − x; x =
18. P = 2b + 2h; b = 21. y = 23 x + 1; x =
B. Solving a pair of linear equations in two
variables:
The solution consists of an ordered pair, an
infinite number of ordered pairs, or no solution.
Problems 22-28: Solve for the common solution(s)
by substitution or linear combinations:
22.
x + 2y = 7
3x − y = 28
23.
x+ y =5
x − y = −3
24. 2x − y = − 9
x =8
2x − y = 1
25.
y = x −5
2
x − 3y = 5
26.
3x + 5 y = 1
4 x −1 = y
4x + y = 1
x+ y =3
28.
x + y =1
2x − y = 3
29.
6x − 9 = 3y
27.
C. Analytic geometry of one linear equation
in two variables:
The graph of y = mx + b is a line with slope m and
y-intercept b. To draw the graph, find one point on
it (such as (0, b)) and then use the slope to find
another point. Draw the line joining the two points.
example: y = −23 x + 5 has
slope −3 2 and y-intercept 5.
To graph the line,
locate (0, 5). From that point,
go down 3 (top of slope fraction),
and over (right) 2
(bottom of fraction)
to find a second point.
Draw the line joining the points.
Problems 30-34: Find slope and y-intercept, and
sketch the graph:
30. y = x + 4
31. y = − 21 x − 3
32. 2 y = 4 x − 8
33. x − y = −1
34. x = −3 y + 2
A vertical line has no slope, and its equation can
be written so it looks like x = k (where k is a
number). A horizontal line has zero slope, and
its equation looks like y = k .
example: Graph on the same graph:
x + 3 = −1 and 1 + y = −3 .
The first equation is x = −4
The second is y = −4
Problems 35-36: Graph and write an equation for…
35. The line through (-1, 4) and (-1, 2)
36. The horizontal line through (4, -1) 8
D. Analytic geometry of two linear equations
in two variables:
Two distinct lines in a plane are either parallel or
intersecting. They are parallel if and only if they
have the same slope, and hence the equations of the
lines have no common solutions. If the lines have
unequal slopes, they intersect in one point and their
equations have exactly one common solution.
(They are perpendicular if and only if their slopes
are negative reciprocals, or one is horizontal and
the other is vertical.) If one equation is a multiple of
the other, each equation has the same graph, and
every solution of one equation is a solution of the
other.
Problems 37-44: For each pair of equations in
problems 22 to 29, tell whether the lines are
parallel, perpendicular, intersecting but not
perpendicular, or the same line:
37.
38.
39.
40.
Problem 22
Problem 23
Problem 24
Problem 25
41.
42.
43.
44.
E. Solution of a one-variable equation
reducible to a linear equation:
Some equations which do not appear to be linear
can be solved by using a related linear equation:
example: 3 − x = 2
Since the absolute value of both 2 and –2 is
2, 3-x can be either 2 or –2. Write these two
equations and solve each:
3− x = 2
3 − x = −2
or −x = −5
−x = −1
x =1
x =5
Problems 45-49: Solve:
48. 2 − 3x = 0
46. x = −1
49. x + 2 = 1
Problems 50-52: Solve and check:
3− x = 4
52. 3 = 3x − 2
2x + 1 = x − 3
50.
51.
if a > b, then :
a+c >b+c
a−c >b−c
ac > bc (if c > 0)
ac < bc (if c < 0)
a
c
a
c
>
<
b
c
b
c
(if c > 0)
(if c < 0)
if a < b, then :
a+c 0)
ac > bc (if c < 0)
a
c
a
c
<
>
b
c
b
c
(if c > 0)
(if c < 0)
example: One variable graph: solve and graph
on a number line: 1− 2x ≤ 7 (This is an
abbreviation for {x: 1 − 2x ≤ 7 })
Subtract 1, get − 2 x ≤ 6
Divide by –2, x ≥ −3
Graph:
-4 -3 -2 -1 0 1 2 3
53.
54.
55.
56.
2x −1 = 5
Answers:
1. 9 2
2. 5 2
3. − 1 3
4. 15 4
5. – 4
6. 5 3
7. 2
8. 13
Be sure to check answer(s):
2x − 1 = 2 •13 − 1
= 25 = 5 (Check)
example: x = −3
x =9
Square:
x = 9 = 3 ≠ −3
Check:
There is no solution, since 9 doesn’t satisfy the
original equation (it is false that 9 = −3).
Problems 53-59: Solve and graph on a number line:
47. x − 1 = 3
example:
Solve:
F. Linear inequalities:
Rules for inequalities:
Problem 26
Problem 27
Problem 28
Problem 29
45. x = 3
2 x −1 = 25
2 x = 26
x = 13
Square both sides:
9.
10.
11.
12.
13.
14.
15.
16.
10
− 54
6
5
− 65
5
3
3
4
180 − a
x −3> 4
4x < 2
2x + 1≤ 6
3< x −3
57. 4 − 2x < 6
58. 5 − x > x − 3
59. x > 1 + 4
17. 90 − a
18. P 2 − h =
19. (y + 2)3
20. 4 − y
21. 3(y −1)2
22. (9, -1)
23. (1, 4)
p− 2h
2 9
33. m = 1, b = 1
24. (8, 25)
25. (-4, -9)
26. (2819 , − 1319)
34. m = −1 3 , b = 2 3
27. (1 4 , 0)
28. no solution
29. (a, 2a − 3), where a is
any number; infinite
number of solutions
30. m = 1, b = 4 4
31. m
= −1
2,
35. x = −1
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
56.
57.
58.
59.
1
2
3
-1
36. y = −1
-1
37.
38.
39.
40.
41.
42.
43.
44.
b = −3
-3
32. m = 2, b = −4
-4
intersecting, not ⊥
⊥
intersecting, not ⊥
intersecting, not ⊥
intersecting, not ⊥
intersecting, not ⊥
parallel
same line
–3, 3
no solution
–2, 4
2
3
–3, -1
–13
no solution in real numbers
11
3
x>7
0
x< 2
x ≤ 52
7
1
x>6
x > −1
x<4
x>5
0
1
0 2 3
0
6
-1
0
0
0
4
5
TOPIC 5: QUADRATIC POLYNOMIALS, EQUATIONS, and INEQUALITIES
example: x − 6x + 9 = (x − 3)
A. Multiplying polynomials:
example:
example:
example:
example:
example:
example:
example:
2
(x + 2) (x + 3) = x 2 + 5x + 6
(2x −1) (x + 2) = 2x 2 + 3x − 2
(x − 5) (x + 5) = x 2 − 25
−4 (x − 3) = −4 x + 12
(x + 2) (x 2 − 2x + 4)= x 3 + 8
2
(3x − 4) = 9x 2 − 24 x +16
(x + 3) (a − 5) = ax − 5 x + 3a − 15
Trinomial:
example: x 2 − x − 2 = (x − 2) (x + 1)
example: 6x 2 − 7x − 3 = (3x + 1) (2x − 3)
Sum and difference of two cubes:
a 3 + b 3 = (a + b) a 2 − ab + b 2
a −b
3
2.
3.
4.
5.
(x + 3) =
2
(x − 3) =
(x + 3)(x − 3) =
(2 x + 3)(2 x − 3) =
(x − 4 )(x − 2) =
2
6. −6x (3 − x ) =
(
9.
)
10.
(x − 12 ) =
2
(x −1)(x + 3) =
(x
2
)(
)
−1 x 2 + 3 =
B. Factoring:
Monomial factors: ab + ac = a(b + c )
example: x 2 − x = x (x − 1)
11.
12.
13.
14.
15.
16.
17.
18.
19.
example: 4 x y + 6 xy = 2 xy (2 x + 3)
2
Difference of two squares: a − b = (a + b)(a − b)
2
2
example: 9 x − 4 = (3 x + 2)(3 x − 2)
2
Trinomial square: a 2 + 2 ab + b 2 = (a + b)
2
a 2 − 2ab + b 2 = (a − b)
2
(
= (a − b) (a
2
)
+ ab + b )
2
(
Problems 11-27: Factor:
7. (2 x − 1) 4 x 2 + 2 x + 1 =
8.
3
)
example: x 3 − 64 = x 3 − 4 3 = (x − 4 ) x 2 + 4 x + 16
Problems 1-10: Multiply:
1.
2
a 2 + ab =
a 3 − a 2b + ab 2 =
8x2 − 2 =
x 2 −10 x + 25 =
−4 xy + 10 x 2 =
2 x 2 − 3x − 5 =
x2 − x − 6 =
x2y − y2x =
8x 3 + 1 =
20.
21.
22.
23.
24.
x 2 − 3 x − 10 =
2x 2 − x =
8x 3 + 8x 2 + 2x =
9 x 2 + 12 x + 4 =
6 x 3y 2 − 9 x 4 y =
25. 1− x − 2 x 2 =
26. 3 x 2 − 10 x + 3 =
27. x 4 + 3 x 2 − 4 =
C. Solving quadratic equations by factoring:
If ab = 0 , then a = 0 or b = 0 .
example: if (3 − x )(x + 2) = 0 then (3 − x ) = 0
or (x + 2) = 0 and thus, x = 3 or x = −2
Note: there must be a zero on one side of the
equation to solve by the factoring method. 10
example: 6x = 3x
6x 2 − 3x = 0
Rewrite:
Factor:
3x (2x − 1) = 0
So 3x = 0 or (2x − 1) = 0
Thus x = 0 or x = 1 2
2
F. Quadratic inequalities:
2
Problems 28-39: Solve by factoring:
28. x (x − 3) = 0
34.
29. x − 2x = 0
35.
(x + 2)(x − 3) = 0
(2 x + 1)(3 x − 2) = 0
36.
37.
38.
39.
6 x2 = x + 2
9 + x 2 = 6x
1− x = 2 x 2
x2 − x −6 = 0
2
30.
31.
32.
33.
2x = x
3x (x + 4 ) = 0
x2 = 2− x
x2 + x = 6
2
x
x < −2
D. Completing the square:
x 2 + bx will be the square of a binomial when c
is added, if c is found as follows: find half the x
coefficient and square it–this is c.
Thus, c =
(b2 )
2
=
b2
4
x + bx + c = x + bx +
2
2
b
4
= (x +
)
b 2
2
example: x + 5x
2
Half of 5 is 5 2 , and (5 2) = 25 4 , which must
be added to complete the square:
2
25
4
= (x +
)
5 2
2
2
If the coefficient of x is not 1, factor it so that it is.
Half of − 1 3 is − 1 6 , and (− 1 6) =
2
(x − x + )= (x − ) , and
3(x − x + )= 3x − x +
1
3
2
Thus
3
36
1
3
(or
1
36
1
36
1
must
12
)
1 2
6
2
1
36 ,
so
3
36
be added to 3x − x to
2
complete the square.
Problems 40-43: Complete the square, and tell
what must be added:
40. x − 10x
2
41. x + x
2
42. x 2 − 23 x
43. 2 x + 8 x
2
E. The quadratic formula:
2
If a quadratic equation looks like ax + bx + c = 0 ,
then the roots (solutions) can be found by using the
quadratic formula: x =
− b ± b 2 − 4 ac
2a
Problems 44-49: Solve:
44. x − x − 6 = 0
2
45. x + 2x = −1
2
46. 2x − x − 2 = 0
2
neg
neg
pos
Solution ?
neg
pos
pos
pos
no
neg
yes
−2 < x < 3
pos
no
x>3
Therefore, if (x − 3)( x + 2) < 0 , then −2 < x < 3
Note that this solution means that x > −2 and x < 3
50. x − x − 6 > 0
2
51. x + 2 x < 0
2
52. x − 2x < −1
2
G. Complex numbers:
−1 is defined to be i, so i 2 = −1
example: i 3 = i 2 • i = −1 • i = −i
4
A complex number is of the form a + bi , where a
and b are real numbers. a is called the real part and b
is the imaginary part. If b is zero, a + bi is a real
number. If a = 0 , then a + bi is pure imaginary.
Complex number operations:
example: (3 + i ) + (2 − 3i ) = 5 − 2i
example: (3 + i ) − (2 − 3i ) = 1 + 4i
2
example: (3 + i)(2 − 3i) = 6 − 7i − 3i
= 6 − 7i + 3 = 9 − 7i
= 23−+3ii • 22++ 33ii = 6+411+i9− 3 = 3+1311i = 133 + 11
example:
i
13
3+ i
2− 3i
Problems 56-65: Write each of the following so
the answer is a+bi:
6
56. (3 + 2i) (3 − 2i) = 61. i =
7
57. (3+ 2i )+ (3− 2i ) = 62. i =
58. (3+ 2i )− (3− 2i ) =
59. (3+ 2i )÷ (3− 2i ) =
60. i =
5
47. x − 3x − 4 = 0
2
48. x + x − 5 = 0
2
49. x + x = 1
2
53. x > x
2
54. 2 x + x −1 > 0
2
55. Find the value of i .
example: 3x 2 − x = 3(x 2 − 13 x)
2
(x − 3) (x + 2) (x − 3) × (x + 2)
Problems 50-54: Solve, and graph on a number line:
, and
2
x 2 + 5x +
example: Solve x − x < 6 . First make one side
2
zero: x − x − 6 < 0
Factor: (x − 3)(x + 2) < 0 .
If (x − 3) = 0 or (x + 2) = 0 then x = 3
or x = −2 .
These two numbers (3 and –2) split the real numbers
into three sets (visualize the number line):
63. i =
8
1991
64. i
65.
1
i
=
=
Problems 66-67: Solve and write the answer as a+bi:
66. x + 2 x + 5 = 0
2
67. x + x + 2 = 0
2 11
Answers:
1. x 2 + 6 x + 9
2. x 2 − 6x + 9
3. x 2 − 9
4. 4 x 2 − 9
5. x 2 − 6x + 8
6. −18 x + 6 x 2
7. 8 x 3 − 1
8. x 2 − x + 14
9. x 2 + 2x − 3
10. x 4 + 2x 2 − 3
11. a (a + b)
(
24. 3 x 3 y (2 y − 3 x )
25. (1− 2x ) (1+ x )
26. (3 x − 1) (x − 3)
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
)
12. a a − ab + b
13. 2(2 x + 1) (2 x − 1)
2
2
14. (x − 5)
15. 2x (−2y + 5x )
2
16. (2 x − 5) (x + 1)
17.
18.
19.
20.
21.
(x − 3)(x + 2)
2
)
+ 4 (x + 1) (x − 1)
2
42. (x − 43 ) , add
2
)
43.
44.
45.
46.
47.
22. 2x (2x + 1)
2
23. (3x + 2)
2
-2 0
1
9
3
51. −2 < x < 0
0, 3
0, 2
0, 1 2
–4, 0
–2, 1
–3, 2
–2, 3
− 12 , 2 3
− 12 , 2 3
3
–1, 1 2
–2, 3
2
(x − 5) , add 25
41. (x + 12 ) , add
xy ( x − y )
(2 x +1) 4 x 2 − 2 x + 1
(x − 5)(x + 2)
x (2 x − 1)
(
(x
48. −1±2 21
49. −1±2 5
50. x < −2 or x > 3
0
-2
52. no solution, no graph
53. 0 < x < 1
0
1
54. x < −1 or x > 1 2
55.
56.
57.
58.
59.
60.
61.
62.
63.
64.
65.
66.
67.
4
16
2(x + 2) , add 8
–2, 3
–1
2
1± 17
4
1
13
6
4i
5
13
+ 12
i
13
i
–1
–i
1
–i
–i
−1 ± 2i
− 12 ± 27 i
–1, 4
TOPIC 6: GRAPHING and the COORDINATE PLANE
A. Graphing points:
1. Join the following points in the given order:
(-3, -2), (1, -4), (3, 0), (2, 3), (-1, 2), (3, 0),
(-3, -2), (-1, 2), (1, -4)
example: A(3, -1), B(-2, 4)
AB =
(4 − (−1)) + (−2 − 3)2 =
2
5 2 + (−5) = 50 = 25 2 = 5 2
2
Problems 7-10: Find the length of the segment
joining the given points:
2. In what quadrant does the point (a, b) lie, if
a > 0 and b < 0 ?
Problems 3-6: For each given point, which of its
coordinates, x or y, is larger? 5
6
4
7. (4, 0), (0, -3)
8. (-1, 2), (-1, 5)
9. (2, -4), (0, 1)
10. − 3, − 5 , 3 3, − 6
(
)(
C. Linear equations in two variables, slope,
intercepts, and graphing:
The line joining the points P1 (x1, y1 ) and
P2 (x 2 , y 2 ) has slope
y 2 − y1
x 2 − x1
.
example: A(3,-1), B(-2,4) slope of
3
B. Distance between points:
The distance between the points P1 (x1, y1 ) and
P2 (x 2 , y 2 ) is found by using the Pythagorean
Theorem, which gives
P1P2 =
(x 2 − x1 )
2
+ (y 2 − y1 ) .
2
____
AB =
4 −(−1)
−2− 3
= −55 = −1
Problems 11-15: Find the slope of the line
joining the given points:
11. (-3, 1), and (-1, -4) 13. (3, -1), and (5, -1)
12. (0, 2), and (-3, 5)
) 12
14.
15.
To find the x-intercept (x-axis crossing) of an
equation, let y be zero and solve for x. For the yintercept, let x be zero and solve for y.
example: 3y − 4 x = 12 if x = 0 , y = 4 so
y-intercept is 4. If y = 0 , x = −3 so xintercept is –3.
The graph of y = mx + b is a line with slope m and
y-intercept b. To draw the graph, find one point on
it (such as (0, b)) and then use the slope to find
another point. Draw the line joining the two.
example: y = −23 x + 5 has slope − 3 2 and yintercept 5. To graph the line, locate (0, 5).
From that point, go down 3 (top of slope
fraction), and over (right) 2 (bottom of
fraction) to find a second point. Join.
Problems 21-25: Find an equation of the line:
21. Through (-3, 1) and (-1, -4)
22. Through (0, -2) and (-3, -5)
23. Through (3, -1) and (5, -1)
24. Through (8, 0), with slope –1
25. Through (0, -5), with slope 2 3
A vertical line has no slope, and its equation can
be written so it looks like x = k (where k is a
number). A horizontal line has zero slope, and
its equation looks like y = k .
example: Graph on the same graph:
x + 3 = −1 and 1 + y = −3 .
The first equation is x = −4 ;
the second is y = −4 .
Problems 26-27: Graph and write equation for:
26. The line through (-1, 4) and (-1, 2)
27. Horizontal line through (4, -1)
D. Linear inequalities in two variables:
example: Two variable graph: graph solution on
a number plane: x − y > 3
(This is an abbreviation for { (x, y ): x − y > 3 }.
Subtract x, multiply by –1, get y < x − 3 .
Graph y = x − 3 ,
but draw a dotted
line, and shade the
side where y < x − 3 :
28. y < 3
29. y > x
30. y ≥ 23 x + 2
Problems 16-20: Find the slope and y-intercept,
and sketch the graph:
16. y = x + 4
17. y = − 12 x − 3
18. 2 y = 4 x − 8
19. x − y = − 1
20. x = −3 y + 2
To find an equation of a non-vertical line, it is
necessary to know its slope and one of its points.
Write the slope of the line through (x, y ) and
the known point, then write an equation which
says that this slope equals the known slope.
example: Find an equation of the line through
(-4, 1) and (-2, 0).
Slope = −14−+02 = −12
Using (-2, 0) and (x, y ),
y−0
Slope = x + 2 = −12 ; cross multiply, get
−2y = x + 2, or y = − 12 x − 1
31. x < y + 1
32. x + y < 3
33. 2 x − y > 1
E. Graphing quadratic equations:
2
The graph of y = ax + bx + c is a parabola, opening
upward (if a > 0 ) or downward (if a < 0 ), and with
line of symmetry. x = −2 ba , also called axis of
symmetry. To find the vertex V(h, k) of the parabola,
h = −2 ba (since V is on the axis of symmetry), and k is
the value of y when h is substituted for x.
example: y = x − 6 x
2
a = 1, b = −6, c = 0
x = −2ab = 62 = 3
Axis: h = 3,
k = 32 −18 = −9
Thus, vertex is (3, − 9) 13
example: y = 3 − x V(0, 3),
2
Axis: x = 0 , y-intercept: if x = 0 , y = 3 − 0 = 3
2
x-intercept: if y = 0 , 0 = 3 − x ,
Problems 34-40: Sketch the graph:
2
34. y = x
35. y = − x
so 3 = x , and x = ± 3
2
38. y = (x + 1)
2
2
36. y = x + 1
2
2
39. y = (x − 2) −1
2
40. y = (x + 2)(x − 1)
37. y = x − 3
2
Answers:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
21.
22.
23.
24.
25.
26.
IV
x
y
y
x
5
3
29
7
− 52
-1
0
− 35
3
y = − 5 2 x − 13 2
32.
y = 23 x − 5
33.
y= x−2
y = −1
y = −x + 8
x = −1 -1
27. y = −1
-1
28.
29.
34.
35.
36.
1
37.
4
m = 1, b = 4
4
30.
38.
17. m = − 1 2 , b = −3
-1
39.
-3
18. m = 2, b = −4
(2,-1)
31.
-4
19. m = 1, b = 1
40.
1
-2
20. m = − 1 3 , b = 2 3
1
2
3
TOPIC 7: LOGARITHMS and FUNCTIONS
A. Functions:
The area A of a square depends on its side
length s, and we say A is a function of s, and
write ‘A = f (s )’; for short, we read this as
‘A = f of s.’ There are many functions of s.
2
2
The one here is s . We write this f (s) = s and
can translate: ‘the function of s we’re talking
2
2
about is s ’. Sometimes we write A (s ) = s .
This says the area A is a function of s, and
2
specifically, it is s .
B. Function values and substitution:
2
If A (s ) = s , A(3), read ‘A of 3’, means replace
2
every s in A (s) = s with 3, and find A when s is 3.
2
When we do this, we find A (3) = 3 = 9 .
example: g(x ) is given: y = g(x ) = π x
2 14
example: g(3) = π • 3 = 9π
Problems 24-28: For this
graph, tell whether the
statement is true or false:
2
example: g(7) = π • 7 2 = 49π
example: g(a) = πa 2
example: g(x + h ) = π(x + h ) = πx 2 + 2πxh + πh 2
2
1. Given y = f (x ) = 3x − 2 .
Complete these ordered pairs: (3,___), (0,___),
( 1 2 ,___), (___, 10), (___,-1) ( x − 1, ___)
Problems 2-10: Given f (x ) = x − 4x + 2 . Find:
2
2. f (0) =
3. f (1) =
4. f (−1) =
5. f (−x ) =
6. − f (x ) =
7. f (x ) − 2 =
8. f (x − 2) =
9. 2 f (x ) =
10. f (2x ) =
Problems 11-15: Given f (x ) =
x
.
x +1
Find:
14. f (−1) =
15. f (x −1) =
11. f (1) =
12. f (−2) =
13. f (0) =
example: If k(x ) = x − 4x , for what x is
k(x ) = 0 ?
2
If k(x ) = 0 , then x − 4 x = 0 and since
2
x − 4x = x (x − 4) = 0 , x can be either 0 or 4.
2
(These values of x: 0 and 4, are called ‘zeros of the
function’, because each makes the function zero.)
Problems 16-19: Find all real zeros of:
16. x (x + 1)
17. 2x 2 − x − 3
27. g(−2) > g(1)
28. g(2) < g(0) < g(4)
24. g(−1) = g(0)
25. g(0) = g(3)
26. g(1) > g(−1)
C. Logarithms and exponents:
Exponential form: 2 = 8
Logarithmic form: log 2 8 = 3
3
Both of the equations above say the same thing.
‘ log 2 8 = 3 ’ is read ‘log base two of eight equals three’
and translates ‘the power of 2 which gives 8 is 3’.
Problems 29-32: Write the following information
in both exponential and logarithmic forms:
29. The power of 3 which gives 9 is 2.
3
30. The power of x which gives x is 3
1
31. 10 to the power –2 is 100
.
32. 12 is the power of 169 which gives 13.
Problems 33-38: Write in logarithmic form:
1
36. 10
= 10−1
37. a b = c
38. y = 3x
33. 4 3 = 64
34. 30 =1
35. 25 = 5 2
Problems 39-44: Write in exponential form:
39. log3 9 = 2
40. log3 1 = 0
41. 5 = log 2 32
42. 1 = log4 4
43. y = loga x
44. logb a = 2
Problems 45-50: Find the value:
48. 6310 =
49. log 49 7 =
50. log 7 49 =
18. x −16x + 64
19. x 2 + x + 2
2
Problems 20-23: Given f (x ) = x − 4x + 2 ,
45. 210 =
46. log 4 410 =
47. log 6 6 =
find real x so that:
D. Logarithm and exponent rules:
exponent rules:
log rules:
all quantities real)
(base any positive real
number except 1)
20. f (x ) = −2
21. f (x ) = 2
2
22. f (x ) = −3
23. x is a zero of f (x )
Since y = f (x ), the values of y are the values of the
function which correspond to specific values of x. The
heights of the graph above (or below) the x-axis are
the values of y and so also of the function. Thus for
this graph, f (3) is the height (value) of the function at
x = 3 and the value is 2: At x = −3 , the value
(height) of f (x ) is zero; in other words, f (− 3) = 0 .
Note that f (3) > f (− 3) , since 2 > 0 , and that
f (0) < f (−1), since f (− 1) = 1 and f (0) < 1.
10
ab • ac = ab+c
ab
= ab− c
ac
(a ) = a
b c
log ab = log a + log b
log ab = log a − log b
log a b = b log a
bc
(ab)
c
= acbc
c
c
(ab ) = ab c
a 0 = 1 (if a ≠ 0)
a− b = a1b
p
log a a b = b
a(log a b ) = b
log b
loga b = log c a
c
( )
p
ar = r ap = r a
(think of rp as power
) (base change rule)
root 15
Problems 51-52: Given log 2 1024 = 10 , find:
51. log 2 1024 5 =
52. log 2 1024 =
Problems 53-63: Solve for x in terms of y and z:
53. 3x = 3y • 3z
55. x 3 = y
54. 9 y =
56. 3x = y
57.
58.
59.
60.
61.
62.
63.
3z
3x
log 7 3 = y; log 7 2 = z; x = log 3 2
y = loga 9; x = log a 3
64. 6 2 x = 6 3
65. 2 2 x = 2 3
74. 5 x +1 = 1
70. 4 3 • 4 5 = 4 x
75. log 3 37 = x
77.
78.
79.
80.
81.
log10 x = log10 4 + log10 2
log 3 2 x = log 3 8 + log 3 4 − 4 log 3 2
log x 25 = 2
3log a 4 = log a x
log(2 x − 6) = log(6 − x )
82.
log x 3
log x 4
84.
= log 4 3
)
88. log 4 64 = x
log 3 81
81
− log 3 27
log 3 27
86. log 2
1
32
=x
87. log16 x =
29. 32 = 9, log 3 9 = 2
30. x 3 = x 3 , log x x 3 = 3
31. 10−2 = 1100 , log10 1100 = −2
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
169
= 13, log169 13 = 1 2
log 4 64 = 3
log 3 1 = 0
log 5 25 = 2
log10 110 = −1
log a c = b
log 3 y = x
32 = 9
30 = 1
2 5 = 32
41 = 4
ay = x
b2 = a
1024
10
1
2 = 1024
10
1
2
2
50
5
4
89.
5 = 5x
= x 90. 27 x =
(19 )
85. log 4 3 30 = x log 4 30 91. 4 10 = 2 x
1/ 2
y+z
z − 2y
x
76. 6(log 6 x ) = 8
(
66. 4 x = 8
67. 9 x = 27 x −1
Answers:
1. 7, -2, − 1 2 , 4, 1 3 , 3x − 5
2. 2
3. –1
4. 7
2
5. x + 4 x + 2
2
6. −x + 4x − 2
2
7. x − 4x
2
8. x − 8x + 14
2
9. 2x − 8x + 4
2
10. 4x − 8x + 2
11. 1 2
12. 2
13. 0
14. no value
15. xx−1
16. –1, 0
17. –1, 3 2
18. 8
19. none
20. 2
21. 0, 4
22. none
23. 2 ± 2
24. F
25. T
26. T
27. T
28. T
69. log 3 4 x = log 3 6
83. log 3 27 • 3−4 = x
E. Logarithmic and exponential equations:
Problems 64-93: Use the exponent and log rules
to find the value of x:
3
73. 5 2
71. 3−2 = x
x
72. 33 = 30
log x 2 = 3log y
log x = 2log y − log z
3log x = log y
log x = log y + log z
log x + log 3 y = log z 2
( ) =5
68. log 3 x = log 3 6
3
2
92. 2 x = 3
93. 3 • 2 x = 4
55. y 3 = 3 y
56. log 3 y
1
57. y 2 = y y
3
58.
y2
z
3
59. y
60. yz
61.
z4
3
62.
z
63.
64.
65.
66.
67.
68.
69.
70.
71.
72.
73.
74.
75.
76.
77.
78.
79.
y
y2
y
2
3
3
3
2
2
2
3
6
3
2
8
1
9
1
6
–1
7
8
8
1
5
3 16
80. 64
81. 4
82. any real number > 0
and ≠ 1
83. –1
84. 1 3
85.
86.
87.
88.
89.
90.
1
91. 20
3
92. log
log 2
3
–5
64
3
1
93.
log 4 − log 3
log 2
(any base; if
base=2, x = 2 − log 2 3)
4
–2
TOPIC 8: WORD PROBLEMS
of 1 6 of 3 4 of a number is 12. What is
the number?
2. On the number line, points P and Q and 2
units apart. Q has coordinate x. What are the
possible coordinates of P?
3. What is the number, which when multiplied
by 32, gives 32 • 46 ?
2
4. If you square a certain number, you get 9 .
What is the number?
1
5. What is the power of 36 that gives 36 2 ?
6. Point X is on each of two given intersecting
lines. How many such points X are there?
7. Point Y is on each of two given circles. How
many such points Y?
8. Point Z is on each of a given circle and a
given ellipse. How many such Z?
9. Point R is on the coordinate plane so its
distance from a given point A is less than 4.
Show in a sketch where R could be.
1.
2
3
Problems 10-11:
B
C
O
A
10. If the length of chord AB is x and length of
CB is 16, what is AC?
11. If AC = y and CB = z , how long is AB (in
terms of y and z)?
12. This square is cut into two smaller squares
and two non-square rectangles as shown.
a
Problems 15-16: x and y are numbers, and two
x’s equal three y’s.
15. Which of x or y must be larger?
16. What is the ratio of x to y?
Problems 17-21: A plane has a certain speed in
still air. In still air, it goes 1350 miles in 3 hours:
17. What is its (still air) speed?
18. How long does it take to fly 2000 miles?
19. How far does the plane go in x hours?
20. If the plane flies against a 50 mph
headwind, what is its ground speed?
21. If it has fuel for 7.5 hours of flying time,
how far can it go against this headwind?
Problems 22-32: Georgie and Porgie bake pies.
Georgie can complete 30 pies an hour:
22.
23.
24.
25.
How many can he make in one minute?
How many can he make in 10 minutes?
How many can he make in x minutes?
How long does he take to make 200 pies?
Problems 26-28: Porgie can finish 45 pies an hour:
26. How many can she make in one minute?
27. How many can she make in 20 minutes?
28. How many can she make in x minutes?
b
a
b
Before being cut, the large square had area
(a + b)2 . The two smaller squares have areas
a2 and b 2 . Find the total area of the two nonsquare rectangles. Do the areas of the 4 parts
add up to the area of the original square?
13. Find x and y:
14. When constructing an equilateral triangle
with an area that is 100 times the area of a
given equilateral triangle, what length should
be used for a side?
Problems 29-32: If they work together, how
many pies can they produce in:
29. 1 minute
30. x minutes
31. 80 minutes
32. 3 hours
Problems 33-41: A nurse needs to mix some
alcohol solutions, given as a percent by weight
of alcohol in water. Thus in a 3% solution, 3%
of the weight would be alcohol. She mixes x
grams of 3% solution, y grams of 10% solution,
and 10 grams of pure water to get a total of 140
grams of a solution which is 8% alcohol: 17
33. In terms of x, how many grams of alcohol
are in the 3% solution?
34. The y grams of 10% solution would include
how many grams of alcohol?
35. How many grams of solution are in the final
mix (the 8% solution)?
36. Write an expression in terms of x and y for
the total number of grams in the 8% solution
contributed by the three ingredients (the 3%,
10%, and water).
37. Use your last two answers to write a ‘total
grams equation’.
38. How many grams of alcohol are in the 8%?
39. Write an expression in terms of x and y for
the total number of grams of alcohol in the
final solution.
40. Use the last two answers to write a ‘total
grams of alcohol equation’.
41. How many grams of each solution are needed?
42. Half the square of a number is 18. What is
the number?
43. If the square of twice a number is 81, what
is the number?
44. Given a positive number x. The square of a
positive number y is at least 4 times x. How
small can y be?
45. Twice the square of half of a number is x.
What is the number?
Problems 46-48: Half of x is the same as onethird of y:
46. Which of x and y is the larger?
47. Write the ratio x : y as the ratio of two
integers.
48. How many x’s equal 30 y’s?
Problems 49-50: A gathering has twice as many
women as men. If W is the number of women
and M is the number of men:
49. Which is correct: 2M=W or M=2W?
50. If there are 12 women, how many men are
there?
Problems 51-53: If A is increased by 25%, it
equals B:
51. Which is larger, B or the original A?
52. B is what percent of A?
53. A is what percent of B?
Problems 54-56: If C is decreased by 40%, it
equals D:
54. Which is larger, D or the original C?
55. C is what percent of D?
56. D is what percent of C?
Problems 57-58: The length of a rectangle is
increased by 25% and its width is decreased by 40%:
57. Its new area is what percent of its old area?
58. By what percent has the old area increased
or decreased?
Problems 59-61: Your wage is increased by
20%, then the new amount is cut by 20% (of the
new amount):
59. Will this result in a wage which is higher
than, lower than, or the same as the original
wage?
60. What percent of the original wage is this
final wage?
61. If the above steps were reversed (20% cut
followed by 20% increase), the final wage
would be what percent of the original wage?
62. Find 3% of 36.
63. 55 is what percent of 88?
64. What percent of 55 is 88?
65. 45 is 3% of what number?
66. The 3200 people who vote in an election are
40% of the people registered to vote. How
many are registered?
67. If you get 36 on a 40-question test, what
percent is this?
68. What is the average of 87, 36, 48, 59, and 95?
69. If two test scores are 85 and 60, what
minimum score on the next test would be
needed for an overall average of 80?
70. The average height of 49 people is 68
inches. What is the new average height if a
78-inch person joins the group?
Problems 71-72: s varies directly as P, and
P = 56 when s = 14 :
71. Find s when P = 144 .
72. Find P when s = 144 .
2
Problems 73-74: A is proportional to r , and
when r = 10 , A = 400π .
73. Find A when r = 15 .
74. Find r when A = 36π
75. If b is inversely proportional to h, and
b = 36 when h = 12 , find h when b = 3 .
76. If 3x = 4 y , write the ratio x : y as the ratio
of two integers. 18
78. After a rectangular piece of knitted fabric
shrinks in length 1 cm and stretches in width 2
cm, it is a square. If the original area was
40 cm 2 , what is the square area?
77. The length of a rectangle is twice the width.
If both dimensions are increased by 2 cm, the
resulting rectangle has area 84 cm 2 . What
was the original width?
Answers:
1. 144
2. x + 2, x − 2
3. 46
4. 9
5. 1 2
6. 1
7. 0,1, or 2
8. 0, 1, 2, 3, or 4
9. Inside circle of radius
4 centered on A
10. x − 16
11. y + z
12. 2ab, yes:
(a + b)2 =
a + 2ab + b
2
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
2
x = 40 7 ; y = 16 3
10 times the original side
x
3
2
450 mph
4 4 9 hours
450x miles
400 mph
3000 miles
1
2
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
5
x
2
400 min.
3
4
15
3x
4
5
4
5x
4
100
225
.03x
.1y
140
x + y + 10
x + y +10 =140
11.2
.03x + .1 y
.03 x + .1 y = 11.2
x = 180 7 ; y = 730 7
6, -6
4.5, -4.5
2 x
2x
y
3: 2 or 3 2
45
2M=W
6
51.
52.
53.
54.
55.
56.
57.
58.
59.
60.
61.
62.
63.
64.
65.
66.
67.
68.
69.
70.
71.
72.
73.
74.
75.
76.
77.
78.
B
125%
80%
C
166 2 3 %
60%
75%
25% decrease
lower
96%
same (96%)
1.08
62.5%
160%
1500
8000
90%
65
95
68.2 inches
36
576
900π
3
144
4:3
5 cm
49
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