GATE Papers >> Civil >> 2007 >> Question No 27

The inverse of the 2 × 2 matrix $\left[\begin{array}{cc}1& 2\\ 5& 7\end{array}\right]$ is

• (A)  $\frac{1}{3}\left[\begin{array}{cc}-7& 2\\ 5& -1\end{array}\right]$   
• (B)  $\frac{1}{3}\left[\begin{array}{cc}7& 2\\ 5& 1\end{array}\right]$   
• (C)  $\frac{1}{3}\left[\begin{array}{cc}7& -2\\ -5& 1\end{array}\right]$   
• (D)  $\frac{1}{3}\left[\begin{array}{cc}-7& -2\\ -5& -1\end{array}\right]$