Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section A

Chapter

Matrices

Question:

If \(A'=\begin{bmatrix}3 & 5\\-6 & 5\end{bmatrix}\) and \(B=\begin{bmatrix}4 & 7\\-1 & 6\end{bmatrix}\) then (AB)' =

Options:

\(\begin{bmatrix}7 & 29\\51 & -12\end{bmatrix}\)

\(\begin{bmatrix}-30 & 55\\-39 & 25\end{bmatrix}\)

\(\begin{bmatrix}47 & 27\\11 & 36\end{bmatrix}\)

\(\begin{bmatrix}18 & 15\\-15 & 65\end{bmatrix}\)

Correct Answer:

\(\begin{bmatrix}18 & 15\\-15 & 65\end{bmatrix}\)

Explanation:

\((AB)'=B'.A'=\begin{bmatrix}4 & -\\7 & 6\end{bmatrix}\begin{bmatrix}3 & 5\\-6 & 5\end{bmatrix}\)

\(\begin{bmatrix}12+6 & 20-5\\21-36 & 35+30\end{bmatrix}=\begin{bmatrix}18 & 15\\-15 & 65\end{bmatrix}\)