If A = ((1,4),(2,3)) then A^2 – 4A = ? ​

Question

If A = \(\begin{pmatrix} 1&4 \\ 2 &3 \end{pmatrix}\) then A² – 4A = ?

A. I 

B. 5I 

C. 3I 

D. 0

Answer 1

A² = \(\begin{pmatrix} 1&4 \\ 2 &3 \end{pmatrix}\)\(\begin{pmatrix} 1&4 \\ 2 &3 \end{pmatrix}\)

= \(\begin{pmatrix} 9&16 \\ 8 &17 \end{pmatrix}\)

= 5I