Question

Completely factor the following expression81y^2-4z^2

Answer 1

difference of two squares
take sqrt of each of the terms

use
a^a + b^2 = (a + b)(a - b)
as a template

Answer 2

Get the square root of \[ \sqrt{81y^2} \] = 9y this is A
Get the square root of \[ \sqrt{4z^2} \] = 2z this is B

Now just plug the numbers into (a + b)(a-b)
(9y+2z)(9y - 2z)