Target Exam

CUET

Subject

-- Applied Mathematics - Section B2

Chapter

Algebra

Question:

If $A=\begin{bmatrix}3&2\\-1&1\end{bmatrix}$ and $B =\begin{bmatrix}-1&0\\2&5\\3&4\end{bmatrix}$, then $(BA)^T$ is equal to:

Options:

$\begin{bmatrix}3&1&5\\2&9&10\end{bmatrix}$

$\begin{bmatrix}-3&1&5\\-2&9&10\end{bmatrix}$

$\begin{bmatrix}-3&-2\\1&9\\5&10\end{bmatrix}$

$\begin{bmatrix}3&2\\1&9\\5&10\end{bmatrix}$

Correct Answer:

$\begin{bmatrix}-3&1&5\\-2&9&10\end{bmatrix}$

Explanation:

The correct answer is Option (2) → $\begin{bmatrix}-3&1&5\\-2&9&10\end{bmatrix}$

$A=\begin{bmatrix}3&2\\-1&1\end{bmatrix}$

$B =\begin{bmatrix}-1&0\\2&5\\3&4\end{bmatrix}$

$BA=\begin{bmatrix}-1&0\\2&5\\3&4\end{bmatrix}\begin{bmatrix}3&2\\-1&1\end{bmatrix}$

$=\begin{bmatrix}-3&-2\\1&9\\5&10\end{bmatrix}$

$⇒(BA)^T=\begin{bmatrix}-3&1&5\\-2&9&10\end{bmatrix}$