# Factor 16x^4-81y^4

Rewrite as .
Rewrite as .
Since both terms are perfect squares, factor using the difference of squares formula, where and .
Simplify.
Remove parentheses.
Rewrite as .
Rewrite as .
Since both terms are perfect squares, factor using the difference of squares formula, where and .
Factor.
Multiply by .
Remove unnecessary parentheses.
Factor 16x^4-81y^4