# How do you factor completely 5x^2-5x-100?

Mar 18, 2018

#### Answer:

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

#### Explanation:

$\textcolor{w h i t e}{\times} 5 {x}^{2} - 5 x - 100$

$= 5 \left({x}^{2} - x - 20\right)$ [First take the common part out]

$= 5 \left\{{x}^{2} - \left(5 - 4\right) x - 20\right\}$ [We can write $1$ as $\left(5 - 4\right)$]

$= 5 \left\{{x}^{2} - 5 x + 4 x - 20\right\}$ [Multiply using Distributive Property]

$= 5 \left\{x \left(x - 5\right) + 4 \left(x - 5\right)\right\}$ [Put the like terms in group]

$= 5 \left(x - 5\right) \left(x + 4\right)$ [Group $\left(x - 5\right)$ terms]

And we got our answer. Hope this helps.