MCQ
If $A=\left[\begin{array}{cc}-2 & 1 \\ 0 & 3\end{array}\right]$ and $f(x)=2 x^2-3 x$, then $f(A)=$
  • A
    $\left[\begin{array}{cc}14 & 1 \\ 0 & -9\end{array}\right]$
  • B
    $\left[\begin{array}{cc}-14 & 1 \\ 0 & 9\end{array}\right]$
  • $\left[\begin{array}{cc}14 & -1 \\ 0 & 9\end{array}\right]$
  • D
    $\left[\begin{array}{cc}-14 & -1 \\ 0 & -9\end{array}\right]$

Answer

Correct option: C.
$\left[\begin{array}{cc}14 & -1 \\ 0 & 9\end{array}\right]$
$\left[\begin{array}{cc}14 & -1 \\ 0 & 9\end{array}\right]$

$\begin{aligned} & f(A)=2 A^2-3 A \\ & =2\left[\begin{array}{cc}-2 & 1 \\ 0 & 3\end{array}\right]\left[\begin{array}{cc}-2 & 1 \\ 0 & 3\end{array}\right]-3\left[\begin{array}{cc}-2 & 1 \\ 0 & 3\end{array}\right] \\ & =2\left[\begin{array}{ll}4 & 1 \\ 0 & 9\end{array}\right]-\left[\begin{array}{cc}-6 & 3 \\ 0 & 9\end{array}\right] \\ & =\left[\begin{array}{cc}8+6 & 2-3 \\ 0-0 & 18-9\end{array}\right]=\left[\begin{array}{cc}14 & -1 \\ 0 & 9\end{array}\right]\end{aligned}$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free