A square matrix $A$ is symmetric if
A$A'=-A$
B$AA'=I$
C$A'=A$
DEvery diagonal entry is zero
Answer & Solution
Correct answer: C. $A'=A$
By definition, a symmetric matrix satisfies $A'=A$, equivalently $a_{ij}=a_{ji}$ for all $i,j$. Option A is the condition for skew-symmetry, and option B is the condition for orthogonality.
Related questions
If a = 2 and b = −3, value of a² − b²:If 0 < a < b and a^2 + b^2 = 50, ab = 7, what is b − a?Solve: |2x − 5| = 3.Expand (x + y)³.If a + b = 7 and ab = 12, find a² + b².If x + 1/x = 3, find x² + 1/x².If x² + y² = 25 and xy = 12, then (x + y)² =If $z=x+iy$, what is the modulus $|z|$?
![](https://qallery.app/diagrams/v2_337fce5574f0/