Target Exam

CUET

Subject

Section B1

Chapter

Matrices

Question:

Find non-zero values of $x$ satisfying the matrix equation $x \begin{bmatrix} 2x & 2 \\ 3 & x \end{bmatrix} + 2 \begin{bmatrix} 8 & 5x \\ 4 & 4x \end{bmatrix} = 2 \begin{bmatrix} (x^2 + 8) & 24 \\ (10) & 6x \end{bmatrix}$.

Options:

2

4

6

8

Correct Answer:

4

Explanation:

The correct answer is Option (2) → 4 ##

Given that,

$x \begin{bmatrix} 2x & 2 \\ 3 & x \end{bmatrix} + 2 \begin{bmatrix} 8 & 5x \\ 4 & 4x \end{bmatrix} = 2 \begin{bmatrix} (x^2 + 8) & 24 \\ (10) & 6x \end{bmatrix}$

$\Rightarrow \begin{bmatrix} 2x^2 & 2x \\ 3x & x^2 \end{bmatrix} + \begin{bmatrix} 16 & 10x \\ 8 & 8x \end{bmatrix} = \begin{bmatrix} 2x^2 + 16 & 48 \\ 20 & 12x \end{bmatrix}$

$\Rightarrow \begin{bmatrix} 2x^2 + 16 & 2x + 10x \\ 3x + 8 & x^2 + 8x \end{bmatrix} = \begin{bmatrix} 2x^2 + 16 & 48 \\ 20 & 12x \end{bmatrix}$

On comparing the corresponding elements of matrices, we get

[∵ both matrices have same order, so corresponding elements are equal]

$\Rightarrow 2x + 10x = 48$

$\Rightarrow 12x = 48$

$\Rightarrow x = \frac{48}{12} = 4$