9w-w^3 I need someone to explain step by step how do I factor this problem

first note that each term has a w in it, so

w(9-w^2)

Now recall that a^2-b^2 = (a-b)(a+b), so since 9-w^2 is the difference of two squares (3^2-w^2), we have

w(3-w)(3+w)