## Introductory Algebra for College Students (7th Edition)

For this problem, we can factor out an $x$ to simplify it: $$x(x + 9) = 0$$ According to the zero product property, the product of factors is zero if at least one factor is zero. Therefore, we can set each factor to zero to solve for $x$: $$x = 0$$ or $$x + 9 = 0$$ We subtract $9$ to each side of the equation to solve for $x$: $$x = -9$$ The solution set is {0, -9}.