Question

How do you factor completely `81 x^4 - 256`?

Answer 1

`(9x^2+16)(3x+4)(3x-4)`

Explanation:

`3^4x^4-16^2`
=`(3x)^4-16^2`
=`(9x^2)^2-16x^2`
=`(9x^2+16)(9x^2-16)`
=`(9x^2+16)(3x+4)(3x-4)`