Matrices
NCERT Class 12
CBSE
Grade 12
Question:
If $\begin{bmatrix} 2x+y & 4x \\ 5x-7 & 4x \end{bmatrix} = \begin{bmatrix} 7 & 7y-13 \\ y & x+6 \end{bmatrix}$, then $x + y$ is equal to:
(a) $5$
(b) $6$
(c) $7$
(d) $4$
Step-by-Step Solution
$y = 5x - 7$. $4x = 7(5x-7) - 13 \Rightarrow 31x = 62 \Rightarrow x = 2, y = 3$. [0.5 Mark]
$x + y = 2 + 3 = 5$. [0.5 Mark]
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🎯 Official CBSE Marking Scheme:
Evaluating $x=2, y=3$: 0.5 Mark
Calculating sum $x+y = 5$: 0.5 Mark
Correct Answer: $5$
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