Inverse matrix of [ * 20 c 4&7 1&2 ] - Vidyadip

MCQ

Inverse matrix of $\left[ {\begin{array}{*{20}{c}}4&7\\1&2\end{array}} \right]$

✓
$\left[ {\begin{array}{*{20}{c}}2&{ - 7}\\{ - 1}&4\end{array}} \right]$
B
$\left[ {\begin{array}{*{20}{c}}2&{ - 1}\\{ - 7}&4\end{array}} \right]$
C
$\left[ {\begin{array}{*{20}{c}}{ - 2}&7\\1&{ - 4}\end{array}} \right]$
D
$\left[ {\begin{array}{*{20}{c}}{ - 2}&1\\7&{ - 4}\end{array}} \right]$

✓

Answer

Correct option: A.

$\left[ {\begin{array}{*{20}{c}}2&{ - 7}\\{ - 1}&4\end{array}} \right]$

a
(a) ${A^{ - 1}} = \frac{{Adj\,(A)}}{{|A|}}$; ${A^{ - 1}} = \left[ {\begin{array}{*{20}{c}}2&{ - 7}\\{ - 1}&4\end{array}} \right]$

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