Factor $ a ^ 3 + 125b ^ 3 $

Question

How to factor using this? $a^3+125b^3$

Using $$a^n+b^n=(a+b)(a^{n-1} - a^{n-2}b + a^{n-3}b^2 - a^{n-4}b^3 + \cdots + b^{n-1})$$

Answer 1

Write $125=5^3$ so that you want to factor $a^3+(5b)^3$. Apply the formula.