# How do you factor  -4x^4+8x^3-20x?

Nov 10, 2015

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

#### Explanation:

Look for anything that can be factored from everything like a $- 4 x$
so $- 4 {x}^{4} + 8 {x}^{3} - 20 x$ becomes $- 4 x \left({x}^{3} - 2 {x}^{2} + 5\right)$

At this point look to see if ${x}^{3} - 2 {x}^{2} + 5$ can be factored, it looks like an ${x}^{2}$ can be taken from ${x}^{3} - 2 {x}^{2}$ which becomes: ${x}^{2} \left(x - 2\right)$

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