Question

express in simplest form: x^3 -16x

Answer 1

first take x out to give

x(x^2 - 16)

now you factor what's in the parentheses

note its the difference of 2 squares: x^2 - 16

can you factor that?

Answer 2

use the identity

a^2 - b^2 = ( a + b)(a - b)

in your case a = x and b = sqrt16 = 4