Solve $y = .13 x^{2} + 20.93 x + 838.43$ $y=.13x^2+20.93x+838.43$ ?

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Answer 1 · 2018-02-08T01:18:41

See below:

I'll assume $y = .13 x^{2} + 20.93 x + 838.43$ $y=.13x^2+20.93x+838.43$ is meant.

$x = \frac{- b \pm \sqrt{b^{2} - 4 a c}}{2 a}$ $x = (-b \pm sqrt(b^2-4ac)) / (2a)$

where we have $a = .13, b = 20.93, c = 838.43$ $a=.13, b=20.93, c=838.43$

$x = \frac{- 20.93 \pm \sqrt{{(20.93)}^{2} - 4 (.13) (838.43)}}{2 (.13)}$ $x = (-20.93 \pm sqrt((20.93)^2-4(.13)(838.43))) / (2(.13))$

$x = \frac{- 20.93 \pm \sqrt{438.0649 - 435.9836}}{.26}$ $x = (-20.93 \pm sqrt(438.0649-435.9836)) / .26$

$x = \frac{- 20.93 \pm \sqrt{2.0813}}{.26}$ $x = (-20.93 \pm sqrt(2.0813)) / .26$

$x = \frac{- 20.93 + \sqrt{2.0813}}{.26} ≅ - 74.95$ $x=(-20.93 + sqrt(2.0813)) / .26 ~=-74.95$

$x = \frac{- 20.93 - \sqrt{2.0813}}{.26} ≅ - 86.05$ $x=(-20.93 - sqrt(2.0813)) / .26 ~=-86.05$

The graph looks like this:

graph{.13x^2+20.93x+838.43[-90,-70,-5,5]}

Solve y=.13x^2+20.93x+838.43y=.13x2+20.93x+838.43y=.13x^2+20.93x+838.43?