#### Answer

$x^3+5x^2+2x−8$

#### 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 polynomials, we must multiply both things in the first set of parenthesis by both things in the second set of parenthesis. Thus, we distribute the x to $(x^2+3x−4)$ and then distribute the 2 to $(x^2+3x−4)$. We then combine like terms to obtain the answer:
$x^3+5x^2+2x−8$