me almost forget, question is to find x and y. not to give
general solution. 
general solution is
y+x^2+2x-8=0
y=-x^2-2x+8
when x=0,
y=8 (ans)
when y=0,
-x^2-2x+8=0
x^2+2x-8=0
using quad formula,
x = -2 +- sqrt[(2^2-4(1)(-8 )] / (2*1)
x = -2 +- sqrt(4+32) / 2
x = 2 or -4 (ans)
so there! 
