University:
Montgomery College
Course:
MATH 130: Elements of Mathematics I: Mathematical Reasoning and Number Systems
Academic year:

2023
Views:

167

Pages:

1
Author:

Dawson Thornton

Mini-Lecture 1.5 Adding Real Numbers Learning Objectives: 1. 2. 3. 4. Add real numbers with the same sign. Add real numbers with unlike signs. Solve problems that involve addition of real numbers. Find the opposite of a number. Examples: 1. Add the following real numbers with the same sign. a) 8 + 11 b) (-3) + (-15) c) (-14) + (-35) ⎛ 3⎞ ⎛ 1⎞ d) ⎜ − ⎟ + ⎜ − ⎟ ⎝ 5⎠ ⎝ 2⎠ 2. Add the following real numbers with different signs. a) (-9) + 5 b) 16 + (-25) c) (-15.3) + 27.03 ⎛1⎞ ⎛ 5⎞ d) ⎜ ⎟ + ⎜ − ⎟ ⎝ 2⎠ ⎝ 8⎠ g) 53 + (-22) ⎛ 5 ⎞ ⎛3⎞ h) ⎜ − ⎟ + ⎜ ⎟ ⎝ 12 ⎠ ⎝ 8 ⎠ Mixed exercise of addition of signed numbers. e) -7 + (-23) f) -42 + 38 3. Solve each of the following. a) At the beginning of a chemistry experiment, Amy measured the temperature of a liquid to be -5°C. During the experiment, the temperature rose 14°C. What was the liquid’s temperature at the end of the experiment? b) A local restaurant reported net incomes of -$1,397, -$2,042, and -$809 for the past three months. What was its total net income for the three months? 4. Find the additive inverse or opposite. a) 8 b) -9 c) 0 d) −17 Teaching Notes: • • • • Some students will need to see addition performed on a number line. Some students will need instruction with inputting negative numbers into a calculator. Review the definition of absolute value. Each section in the text has 3 worksheets in the Extra Practice featuring differentiated learning. Answers: 1a) 19; 1b) -18; 1c) –49; 1d) -11/10; 2a) -4; 2b) -9; 2c) 11.73; 2d) -1/8; 2e) -30; 2f) -4; 2g) 31; 2h) -1/24; 3a) 9° C; 3b) -$4,248; 4a) -8; 4b) 9; 4c) 0; 4d) -17