80.2k views
1 vote
What is x^2+x-20=0.
please help

User Bill Mei
by
7.0k points

1 Answer

4 votes
x² + x - 20 = 0

x² = x * x
x = the sum of the factors of -20
-20 ⇒ 1 x 20
2 x 10
- 4 x 5 ⇒ only these factors can arrive to a sum of 1

(x - 4)(x + 5) = x(x+5) - 4(x+5) = x² + 5x - 4x - 20 = x² + x - 20

x - 4 = 0
x = 4

x + 5 = 0
x = -5
User Jack Parkinson
by
7.6k points