Question 11171
The expression is the difference of two cubes which is factored as follows:

{{{(a^3 - b^3) = (a - b)(a^2 + ab + b^2)}}} Applying this to your problem: 


{{{x^3 - 125 = x^3 - 5^3}}} = {{{(x - 5)(x^2 + 5x + 25)}}}