If matrix A = [ * 20 c 3&2&4 1&2& - 1 0&1&1 ]and A^ - 1 = 1 K adj… - Vidyadip

MCQ

If matrix $A = \left[ {\begin{array}{*{20}{c}}3&2&4\\1&2&{ - 1}\\0&1&1\end{array}} \right]$and ${A^{ - 1}} = \frac{1}{K}adj(A),$ then $K$is

A
$7$
B
$-7$
C
$\frac{1}{7}$
✓
$11$

✓

Answer

Correct option: D.

$11$

d
(d)$K = \,|A|$; $|A|\,\, = \left| {\,\begin{array}{*{20}{c}}3&2&4\\1&2&{ - 1}\\0&1&1\end{array}\,} \right|\, = \,\,11$.

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