Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Matrices

Question:

If $\begin{bmatrix} 2 & -1\\1 & 0\\-3& 4\end{bmatrix} A= \begin{bmatrix} -1 & -8 & -10\\1 & -2 & -5 \\9 & 22 & 15 \end{bmatrix}$ , then matrix A is equal to :

Options:

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

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

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

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

Correct Answer:

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

Explanation:

The correct answer is Option (3) → $\begin{bmatrix} 1 & -2 & -5\\3 & 4 & 0\end{bmatrix}$

Method of deviation (B & D) can't be answers and using hit and trial with option A and C

we get

$\begin{bmatrix} 2 & -1\\1 & 0\\-3& 4\end{bmatrix}\begin{bmatrix} 1 & -2 & -5\\3 & 4 & 0\end{bmatrix}=\begin{bmatrix} -1 & -8 & -10\\1 & -2 & -5 \\9 & 22 & 15 \end{bmatrix}$

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