WAEC 2020 · Paper 1 · Q5

If $\begin{pmatrix} p + q & 1 \\ 0 & p - q \end{pmatrix} = \begin{pmatrix} 2 & 1 \\ 0 & 8 \end{pmatrix}$ , find the values of $p$ and $q$ .

Worked solution (try it first)

Equal matrices have equal entries in matching places: $p + q = 2$ and $p - q = 8$ .
Add the two equations: $2p = 10$ , so $p = 5$ .
Then $q = 2 - 5 = -3$ .
So $p = 5$ , $q = -3$ , option B.