How do you solve x^2+x-20=0?

Mar 28, 2016

$x = 4 , - 5$

Explanation:

color(blue)(x^2+x-20=0

First, Factor the equation:

$\rightarrow {x}^{2} + 5 x - 4 x - 20 = 0$

$\rightarrow x \left(x + 5\right) - 4 \left(x + 5\right) = 0$

color(purple)(rarr(x-4)(x+5)=0

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Next, set both equations equal to zero, and solve.

$\rightarrow x - 4 = 0$

Add four to each side, and solve:

$\rightarrow x \cancel{- 4 + 4} = 0 + 4$

color(green)(rArrx=4

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$\rightarrow x + 5 = 0$

Subtract $5$ from each side, and solve:

$\rightarrow x \cancel{+ 5 - 5} = 0 - 5$

color(green)(rArrx=-5

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:.color(indigo)( ul bar |x=4, -5|