Question

If a matrix A is symmetric as well as skew-symmetric, then A is a 

(A) Diagonal matrix 

(B) Null matrix 

(C) Unit matrix 

(D) None of these 

Answer 1

Answer is (B) Null matrix

Let A be symmetric as well as skew-symmetric matrix. 

Then  A' = and A' = - A

⇒ A = -A or 2A = 0 or A = 0