Answer
$x^{2} +9x+18$
Work Step by Step
In order to multiply binomials, we use the distributive property. However, recall that in order to use the distributive property with binomials, we must multiply both things in the first set of parenthesis by both things in the second set of parenthesis. Thus, using the FOIL method, we expand $(x+6)(x+3)$. We then combine like terms to obtain the answer:
$x^{2} +9x+18$