how do you solve this system? I'm using substitution..

y=3x+4
y=-x^2

First I combined it: -x^2=3x+4

I don't know how to solve it now..

3 answers

make it a quadratic equation..

x^2+3x+4=0
Now, use the quadratic formula. I think it will have complex roots.
Get all of the terms to the left side by adding -3x and -4 to both sides.
-x^2 - 3x - 4 = 0

divide through by -1 (divide each term by -1)
x^2 + 3x + 4 = 0

factor the trinomial
(x + 3)(x + 1) = 0

see if you can take it from there.
Rick, that factorization is wrong.