If $A$ and $B$ are two square matrices with $\operatorname{det} A=5$ and $\operatorname{det}\left(B^T \cdot…

If $A$ and $B$ are two square matrices with $\operatorname{det} A=5$ and $\operatorname{det}\left(B^T \cdot A^T\right)=-15$, then $\operatorname{det} B$ is equal to
  1. 3
  2. -3
  3. 0
  4. 1

Solution

Given, $|A|=5 ;\left|B^T A^T\right|=-15$ We know $|A|=\left|A^T\right|$ $\begin{aligned} \therefore \quad\left|B^T\right|\left|A^T\right| & =|B||A|=-15 \\ |B| & =\frac{-15}{|A|}=\frac{-15}{5}=-3\end{aligned}$

Asked in: AP EAMCET 2021 (25 Aug Shift 1)

Practice more Determinants questions on Aicharya