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MATRICES — Maths STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceMathsMATRICES1 Mark
MCQ
If $\text{A}=\begin{bmatrix}0&2\\3&-4\end{bmatrix}$ and $\text{kA}=\begin{bmatrix}0&3\text{a}\\2\text{b}&24\end{bmatrix},$ then the values of k, a, b, are respectively
  • A
    -6, -12, -18
  • B
    -6, 4, 9
  • ✓
    -6, -4, -9
  • D
    -6, 12, 18
✓

Answer

Correct option: C.
-6, -4, -9
$\text{A}=\begin{bmatrix}0&2\\3&-4\end{bmatrix}$

$\text{kA}=\begin{bmatrix}0&3\text{a}\\2\text{b}&24\end{bmatrix}$

$\Rightarrow\begin{bmatrix}0&2\text{k}\\3\text{k}&-4\text{k}\end{bmatrix}=\begin{bmatrix}0&3\text{a}\\2\text{b}&24\end{bmatrix}$

$\Rightarrow-4\text{k}=24$

$\Rightarrow\text{k}=-6$

$2\text{k}=3\text {a}$

$\Rightarrow\text{a}=-4$

$3\text{k}=2\text{b}$

$\Rightarrow\text{b}=-9$

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