# How do you factor 5x^3+15x^2-20x?

May 26, 2018

$5 x \left(x + 4\right) \left(x - 1\right)$

#### Explanation:

$\text{take out a "color(blue)"common factor } 5 x$

$= 5 x \left({x}^{2} + 3 x - 4\right)$

$\text{the factors of - 4 which sum to + 3 are +4 and - 1}$

$= 5 x \left(x + 4\right) \left(x - 1\right)$

May 26, 2018

$5 x \left(x - 1\right) \left(x + 4\right)$

#### Explanation:

We get
$5 x \left({x}^{2} + 3 x - 4\right)$
Solving
${x}^{2} + 3 x - 4 = 0$
we obtain
$x = 1$
or
$x = - 4$
so finally we get
$5 x \left(x - 1\right) \left(x + 4\right)$

May 26, 2018

5x^3+15^2-20x=color(blue)(5x(x+4)(x-1)

#### Explanation:

Factor:

$5 {x}^{3} + 15 {x}^{2} - 20 x$

Factor out the GCF $5 x$.

$5 x \left({x}^{2} + 3 x - 4\right)$

Find two numbers that when added equal $3$, and when multiplied equal $- 4$. The numbers $4$ and $- 1$ meet the requirements.

$5 x \left(x + 4\right) \left(x - 1\right)$