posted by JustinBieber on .
Pls show me steps
This is a difference of cubes which has the pattern
A^3 - B^3 = (A-B)(A^2 + AB + B^2)
= (2x - 5)(4x^2 + 10x + 25)
you have a typo in your second, but it looks like there would be a common factor.