Question

If the value of $p^2+q^2=21$ and $pq=30$, then find the value of $(p+q{)}^2$. [2 marks]

Answer 1

Given,
$p^2+q^2=21$ , $pq=30$

We know that,
$(p+q{)}^2=p^2+q^2+2pq$ ( 1 mark )
$(p+q{)}^2=21+2\times 30$
$(p+q{)}^2=21+60$
$(p+q{)}^2=81$ (1 mark)