If A = [ * 20 c 1/3 &2 0& 2x - 3 ],B = [ * 20 c 3&6 0& - 1 ]and A… - Vidyadip

MCQ

If $A = \left[ {\begin{array}{*{20}{c}}{1/3}&2\\0&{2x - 3}\end{array}} \right],B = \left[ {\begin{array}{*{20}{c}}3&6\\0&{ - 1}\end{array}} \right]$and $AB = I$, then $x =$

A
$-1$
✓
$1$
C
$0$
D
$2$

✓

Answer

Correct option: B.

$1$

b
(b) $\left[ {\begin{array}{*{20}{c}}
{1/3}&2 \\
0&{2x - 3}
\end{array}} \right]\left[ {\begin{array}{*{20}{c}}
3&6 \\
0&{ - 1}
\end{array}} \right] = \left[ {\begin{array}{*{20}{c}}
1&0 \\
0&{3 - 2x}
\end{array}} \right] = I = \left[ {\begin{array}{*{20}{c}}
1&0 \\
0&1
\end{array}} \right]$

(As given)

$\Leftrightarrow \,\,3 - 2x = 1$ or $x = 1$.

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