alleryIf $A$ is skew-symmetric, which of the following must be true?
A$A'=A$
B$A'=-A$
C$AA'=I$
DEvery entry of $A$ is positive
Answer & Solution
Correct answer: B. $A'=-A$
A skew-symmetric matrix is defined by the condition $A'=-A$, or equivalently $a_{ij}=-a_{ji}$.
It is different from a symmetric matrix, which satisfies $A'=A$.
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