x*y = 2
y - = 8 x
y/x = 8
-0.5
-4
0.5
4
x1 = -0.5 y1 = -4.0
x2 = -0.4999999999997398 y2 = -4.000000000000247
x3 = 0.5 y3 = 4.0
x4 = 0.4999999999997398 y4 = 4.000000000000247