Determinants
NCERT Exemplar Class 12
CBSE
Grade 12
Question:
If matrix $A = \begin{bmatrix} 2 & 3 \\ 5 & -2 \end{bmatrix}$ and $A^{-1} = k A$, then $k$ is equal to:
(a) $\dfrac{1}{19}$
(b) $19$
(c) $-\dfrac{1}{19}$
(d) $-19$
Step-by-Step Solution
|A| = -19, adj A = -A \implies A^{-1} = (1/19) A. [1.0 Mark]
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🎯 Official CBSE Marking Scheme:
Selecting $\dfrac{1}{19}$: 1.0 Mark
Correct Answer: $\dfrac{1}{19}$
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