# How do you multiply (x+4)(x^2 +2x - 5)?

Jun 25, 2015

 = color(blue)(x^3 + 6x^2 + 3x -20

#### Explanation:

$\textcolor{b l u e}{\left(x + 4\right)} \left({x}^{2} + 2 x - 5\right)$

• Here, we first multiply $\textcolor{b l u e}{x}$contained in the first bracket with all three terms of second bracket:

$= \textcolor{b l u e}{x} . \left({x}^{2}\right) + \textcolor{b l u e}{x} . \left(2 x\right) + \textcolor{b l u e}{x} . \left(- 5\right)$

$= {x}^{3} + 2 {x}^{2} - 5 x$........................$\left(1\right)$

• Now, we multiply $\textcolor{b l u e}{4}$ contained in the first bracket with all three terms of second bracket:

$= \textcolor{b l u e}{4} . \left({x}^{2}\right) + \textcolor{b l u e}{4} . 2 x + \textcolor{b l u e}{4} . \left(- 5\right)$

$= 4 {x}^{2} + 8 x - 20$.........................$\left(2\right)$

combining $\left(1\right)$ and $\left(2\right)$

 = color(blue)(x^3 + 6x^2 + 3x -20