JAMB 2013 · UTME · Q22

If $P = \begin{pmatrix} 5 & 3 \\ 2 & 1 \end{pmatrix}$ and $Q = \begin{pmatrix} 4 & 2 \\ 3 & 5 \end{pmatrix}$ , find $2P + Q$ .

Worked solution (try it first)

Double every entry of $P$ : $2P = \begin{pmatrix} 10 & 6 \\ 4 & 2 \end{pmatrix}$ .
Add $Q$ entry by entry, in matching positions: $\begin{pmatrix} 10 + 4 & 6 + 2 \\ 4 + 3 & 2 + 5 \end{pmatrix}$ .
So $2P + Q = \begin{pmatrix} 14 & 8 \\ 7 & 7 \end{pmatrix}$ , option D.