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Model Paper 4 — Maths STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceMathsModel Paper 41 Mark
MCQ
If the matrix $A=\left[\begin{array}{cc}3-2 x & x+1 \\ 2 & 4\end{array}\right]$ is singular then $x =?$
  • ✓
    $1$
  • B
    $0$
  • C
    $-1$
  • D
    $-2$
✓

Answer

Correct option: A.
$1$
When a given matrix is singular then the given matrix determinant is $0.$
$|A|=0$
Given, $A=\left(\begin{array}{cc}3-2 x & x+1 \\ 2 & 4\end{array}\right)$
$|A|=0$
$4(3-2 x)-2(x+1)=0$
$12-8 x-2 x-2=0$
$10-10 x=0$
$10(1-x)=0$
$x=1$

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