Question

If A = $\begin{bmatrix} 4 & 2 \

• 1 & 1 \end{bmatrix}$, then (A –2I) (A –3I) =

• A. A
• B. I
• C. 0
• D. 5I

Answer 1

Answer: (C)

0

Answer 2

$\left( \begin{bmatrix} 4 & 2 \

• 1 & 1 \end{bmatrix} - 3\begin{bmatrix} 1 & 0 \ 0 & 1 \end{bmatrix} \right)$

= $\left[ \begin{array} { c c } 2 & 2 \\ - 1 & - 1 \end{array} \right]$ $\begin{bmatrix} 1 & 2 \

• 1 & - 2 \end{bmatrix}$=$\begin{bmatrix} 0 & 0 \ 0 & 0 \end{bmatrix}$= 0