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Determinants — Maths STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceMathsDeterminants1 Mark
MCQ
Find the value of $x,$ if $\begin{bmatrix}2&5\\3&\text{x}\end{bmatrix}=\begin{bmatrix}\text{x}&-1\\5&3\end{bmatrix}$ is:
  • ✓
    $20$
  • B
    $-20$
  • C
    $30$
  • D
    $-30$
✓

Answer

Correct option: A.
$20$
$\begin{bmatrix}2&5\\3&\text{x}\end{bmatrix}=\begin{bmatrix}\text{x}&-1\\5&3\end{bmatrix}$
$\Rightarrow2\text{x}-15=3\text{x}+5 $
$\Rightarrow\text{x}=-20$

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