7x^2- 448 Factor the following.

7(x^2-64) = 7(x+8)(x-8)

7(x+8) (x-8)

divide by 7
x^2-64.
What else do you need?

I always use wolfram alpha too for double checking!

7x^2 - 448
= 7(x^2 - 64)
= 7( x + 8)(x - 8)