I know how to expand when the expression is like: $$a^2-b\qquad\text{ which expands to }\qquad(a+b^{1/2})(a-b^{1/2})$$ or like $$a^4-b\qquad\text{ which expands to }\qquad(a^2+b^{1/2})(a^2-b^{1/2})$$
But what is the method / formula to expand expressions like:
$$a^3-b$$
I would assume its something like the product of a quadratic and a binomial but I am not sure how to get there.