| A1xyz5 + B1x + C1y + D1 | = | 0 |
| A2xyz5 + B2x + C2y + D2 | = | 0 |
| A3xyz5 + B3x + C3y + D3 | = | 0 |
z5 = a, x = b, y = c, (some a, b, c)
which has 1 real root.
| A1x + B1y + C1(z) | = | 0 | |
| A2x + B2y + C2(z) | = | 0 | (deg(Ci(z))=5) |
| A3x + B3y + C3(z) | = | 0 |
f(z) = 0, x = g(z), y = h(z), (deg(f)=5)
which can have 5 real roots.