Question

Find the following squares by using identities:
$(xy+3z{)}^2$

Answer 1

Since, we know that $(a+b{)}^2=a^2+2ab+b^2$
Substitute $a=xy,b=3z$, we get
($xy+3z{)}^2=(xy{)}^2+2\times xy\times 3z+(3z{)}^2$
$\therefore (xy+3z{)}^2=x^2{y}^2+6xyz+9z^2$