Question

Factor completely. 5x^2 - 45

Answer 1

Simple...

you have: $5 x^{2} -45$

Using the box method-->>

5(x+3)(x-3)

Thus, your answer.

Answer 2

Hint:  Divide both terms by 5 (that is, factor the 5 out of the given expression).

You will then have 5(x^2-9).  Factor (x^2-9) now.