JEE Mains · Maths · STD 12 - 3 and 4 . metrices and determinant
If \(A=\left(\begin{array}{ll}{2} & {2} \\ {9} & {4}\end{array}\right)\) and \(I=\left(\begin{array}{ll}{1} & {0} \\ {0} & {1}\end{array}\right),\) then \(10 A^{-1}\) is equal to
- A \(4I-A\)
- B \(A-6I\)
- C \(6I-A\)
- D \(A-4I\)
Answer & Solution
Correct Answer
(B) \(A-6I\)
Step-by-step Solution
Detailed explanation
\(A=\left(\begin{array}{ll}{2} & {2} \\ {9} & {4}\end{array}\right) ;|A|=8-18=-10\) \(A^{-1}=\frac{\operatorname{adj} A}{|A|}=\frac{\left(\begin{array}{cc}{4} & {-2} \\ {-9} & {2}\end{array}\right)}{-10}\)…
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