Q72 / 180 · KCET 2019 · Mathematics

If \( P \) and \( Q \) are symmetric matrices of the same order then \( P Q-Q P \) is

  • A
    symmetric matrix
  • Correct answer
    B
    skew symmetric matrix
  • C
    identity matrix
  • D
    zero matrix

Solution

(B) Given $P=P^{\prime}$ and $Q=Q^{\prime}$ $(P Q-Q P)^{\prime}=(P Q)^{\prime}-(Q P)^{\prime}$ $=\left(Q^{\prime} P^{\prime}-P^{\prime} Q^{\prime}\right)$ $=Q P-P Q$ $=-[P Q-Q P]$ $\therefore(P Q-Q P)$ is skew symmetric.

Hence, the correct answer is option: 'B'.

Relevant Questions