Question

Solve the system:
y = 2x^2 + 2x - 1
y = -x^2 -x +5

Answer 1

This is what I have so far:

-x^2 - x + 5 = 2x^2 + 2x -1
0 = x^2 + x - 5 + 2x^2 + 2x- 1
0 = 3x^2+ 3x - 6

Answer 2

do i just do the quadratic formula?

Answer 3

Factor the 3 out first.

Answer 4

3x^2+ 3x - 6 = 0
3(x^2 + x - 2) = 0
x^2 + x - 2 = 0
x^2 + 2x - x - 2 = 0
x(x + 2) - 1(x + 2) = 0
(x+2)(x-1) = 0
x = -2 or 1.

Answer 5

wait where did the 2x come from?

Answer 6

It is a way to factor a quadratic equation.
The middle term x can be written as 2x - x

Answer 7

http://www.purplemath.com/modules/factquad.htm

Answer 8

ah thank you so much! :)

Answer 9

You are welcome.