Question

x power4 -(x-z)power4

Answer 1

I hope it is helpful for you

Answer 2

x power 4 - (x-z)power 4 = (x²)² - ((x-z)²)²        Take it as a²-b²= (a+b)(a-b)
                                                                         Where a = x² , b= (x-z)²
Therefore , (x²+(x-z)²) (x²-(x-z)²)                     Take (x-z)² as (a-b)² = a²-2ab+b²
(x²+(x²-2xz+z²) (x²-(x²-2xz+z²)) = (x²+x²-2xz+z²)(x²-x²-2xz+z²)
= (2x²-2xz+z²) (-2xz +z²) = Here ; -2xz gets cancelled 
∴ The solution is   "z²(2x²-2xz)"