Question

5x​2​​−320 factored completely?

Answer 1

First factor out the 5 so you have 5(x2-64). Since (a+b)(a-b)=(a^2-b^2)
(x^2-64)=(x-8)(x+8). So completely factored is 5(x-8)(x+8).

Answer 2

First take out the GCF (5)
5(x^2-64)
It's a perfect square so we can go further
5(x+8)(x-8)