How do you factor $- 5 x^{2} - x + 4$ $-5x^2 - x + 4$ ?

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Answer 1 · 2017-03-29T21:31:00

$(- 5 x - 4) (x + 1)$ $(-5x-4)(x+1)$

First, you would find the zeros by applying the quadratic formula:

$x = \frac{1 \pm \sqrt{1 - 4 (- 5) 4}}{2 (- 5)}$ $x=(1+-sqrt(1-4(-5)4))/(2(-5))$

$x = \frac{1 \pm 9}{- 10}$ $x=(1+-9)/-10$

$x_{1} = \frac{1 - 9}{- 10} = - \frac{8}{- 10} = \frac{4}{5}$ $x_1=(1-9)/-10=-8/-10=4/5$

$x_{2} = \frac{1 + 9}{- 10} = - 1$ $x_2=(1+9)/-10=-1$

Then you could apply the formula and factor:

$a x^{2} + b x + c = a (x - x_{1}) (x - x_{2})$ $ax^2+bx+c=a(x-x_1)(x-x_2)$

$- 5 x^{2} - x + 4 = - 5 (x - \frac{4}{5}) (x + 1)$ $-5x^2-x+4=-5(x-4/5)(x+1)$

$= (- 5 x - 4) (x + 1)$ $=(-5x-4)(x+1)$

How do you factor −5x2−x+4-5x^2 - x + 4?