if you're solving for x,
start by isolating x squared to get
x^2 = 16 (we added 8 to both sides)
then square root each side:
sqrt of x^2 = x; sqrt of 16 = 4.
we end up with x = 4 (positive and neg)
if you're factoring
minus 8 from both sides to get
x^2 - 16
from there we can factor to get
(x + 4)(x - 4)
