How do you solve y^2+y=20?

2 Answers
Dec 21, 2017

y^2 +y = 20

y^2 + y - 20 =0

What 2 numbers add to +1 and multiply to -20?

+5 and -4.

Therefore,

(y+5)(y-4) = 20

Therefore, y can be color(red)(-5 or, +4

Dec 21, 2017

y = -5, 4

Explanation:

y^2+y=20.

Subtracting 20 From Both Sides,

y^2+y-20 = 0.

Factoring,

(y+5)(y-4) = 0.

Since One Of The Answers Have To Be 0,

y+5 = 0, y = -5

y-4 = 0, y = 4

The Answers Are: -5 and 4.