Question

factorise the following question: 2z^2-18

Answer 1

2$z^{2}$-18=0
=2$z^{2}$-2$3^{2}$=0
=2($z^{2}$-$3^{2}$)=0
=2(z+3)(z-3)=0
=(z+3)(z-3) are the factors!

Answer 2

2z^2-18
=2[(z-3)(z+3)]

Hope this helps!!