Show that the graph of an equation of the form 

Ax² + Cy² + Dx + Ey + F = 0, A ≠ 0, C ≠ 0,

(a) Is a hyperbola if D²/4A + E²/4C – F ≠ 0.

(b) Is two intersecting lines if D²/4A + E²/4C – F = 0