Question

Use square too property: 3z^2-63=0 the 63...err i got lost there :( Do i square it or what?

Answer 1

3z^2 = 63

z^2 = 21
z = \[\pm \sqrt{21}\]

Answer 2

how did you come by the 21? thanks :)

Answer 3

Moneybird took

3z^2 = 63 divide both sides by 3
z^2 = 21 Take square roots of both sides
z = sqrt(21)
and
z = -sqrt(21)