## Precalculus (6th Edition) Blitzer

$(3x – 5)(9x^2 + 15x + 25)$
Recall that $a^3 – b^3 = (a – b)(a^2 + ab + b^2)$. $27x^3-125$ can be rewritten as $(3x)^3-5^3$ We use this to simplify the expression: $27x^3-125=(3x – 5)((3x)^2 + 3x(5) + 5^2)=(3x – 5)(9x^2 + 15x + 25)$