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Question: Answered & Verified by Expert
If matrix $A=\left[\begin{array}{ll}a & b \\ c & d\end{array}\right]$, then $|A|^{-1}$ is equal to
MathematicsMatricesMHT CETMHT CET 2010
Options:
  • A $a d-b c$
  • B $\frac{1}{a d-b c}$
  • C $\frac{1}{a d-b c}\left[\begin{array}{rr}d & -b \\ -c & a\end{array}\right]$
  • D None of these
Solution:
2587 Upvotes Verified Answer
The correct answer is: $\frac{1}{a d-b c}$
Given, $\quad A=\left[\begin{array}{ll}a & b \\ c & d\end{array}\right]$
$$
\begin{array}{l}
|A|=a d-b c \\
|A|^{-1}=\frac{1}{a d-b c}
\end{array}
$$

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