Chapter 4 Quadratic Functions and Factoring - 4.3 Solve x(squared) + bx + c = 0 - 4.3 Exercises - Skill Practice - Page 255: 13

$$(x+12)(x-3)$$

Since the coefficient of the squared term is one, we know that the expression must factor to: $$ (x\pm a)(x\pm b)$$ Here, we see that a and b must multiply to get $-36$ and add to get $9$. Thus, we find that the solution is: $$(x+12)(x-3)$$