If $A=\left[\begin{array}{ll}0 & 1 \\ 1 & 0\end{array}\right]$, then the value of $(A+I)^3-4 A$ is |
$8 A$ $4 I$ $8 A+4 I$ $3 A+I$ |
$4 I$ |
The correct answer is Option (2) - $4 I$ $A^2=\left[\begin{array}{ll}0 & 1 \\ 1 & 0\end{array}\right]\left[\begin{array}{ll}0 & 1 \\ 1 & 0\end{array}\right]=\left[\begin{array}{ll}1 & 0 \\ 0 & 1\end{array}\right]=I$ so $(A+I)^3-4A$ $=(A+I)^2+(A+I)-4A$ $(A^2+I^2+AI+IA)(A+I)-4A$ $2(A+I)^2-4A$ $4(A+I)-4A=4I$ |