MATH 462, Quiz 5
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Name: (print) _________________
Each problem is worth 2 points. Show all your work.
1. A matrix A E 111nxn (C) is skew-symmetric if A T = -A. (a) Prove that if A is skew
symmetric and n is odd then A is not invertible. (b) Give an example of an invertible
skew-symmetric matrix in the case when n is even.
A T==-A
,ck-t AT
:c
t':kt (-A)
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det(A) =tr/' d.et(A)
rr"7!J
,'I' ()✓o r
1f n
cktfA)�
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- det(A)
A 1:S
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:=;
2-
A-�(!,:)
2olet(A)= 0
0
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(olet (t1) � I )
2. Let A, B E Mn x n (lF) be such that AB = -BA. Prove that if n is odd, and IF is not a
flield of characteristic two, then A or B is not invertible.