You can
put this solution on YOUR website!
x² – 16
(x + 4)(x - 4)
Check it by FOILing it out and seeing if you get the original.
(x + 4)(x - 4) = x² - 4x + 4x - 16.
That simplifies after cancelling the -4x and the +4x to
x² - 16, which is what you started with, so it is correct.
Edwin