solve the system of equations:
x^(2)+y^(2) = 12
xy = -4
Use substitution.
y = -4/x
x^2 + 16/x^2 = 12
let u = x^2
u + 16/u = 12
u^2 -12u + 16 = 0
u = (1/2)[12 +/-sqrt80]
= 10.47 or 1.527
x = +/-1.236 or +/-3.236
Get y for each x using
y = -4/x