Question:

If \[ \begin{bmatrix} x+y & 2 1 & x-y \end{bmatrix} = \begin{bmatrix} 4 & 2 1 & 2 \end{bmatrix}, \] then the values of \(x\) and \(y\) are:

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When two matrices are equal, compare corresponding entries to form equations.
  • \(x=3,\ y=1\)
  • \(x=1,\ y=3\)
  • \(x=2,\ y=3\)
  • \(x=1,\ y=1\)
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The Correct Option is A

Solution and Explanation

Concept: Two matrices are equal if all their corresponding elements are equal.

Step 1:
Compare corresponding elements of both matrices. \[ \begin{bmatrix} x+y & 2 1 & x-y \end{bmatrix} = \begin{bmatrix} 4 & 2 1 & 2 \end{bmatrix} \] From the first row and first column: \[ x+y=4 \quad \cdots (1) \] From the second row and second column: \[ x-y=2 \quad \cdots (2) \]

Step 2:
Add equations (1) and (2). \[ (x+y)+(x-y)=4+2 \] \[ 2x=6 \] \[ x=3 \]

Step 3:
Substitute \(x=3\) in equation (1). \[ 3+y=4 \] \[ y=1 \] Therefore, \[ \boxed{x=3,\ y=1} \]
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