| Exam Board | CAIE |
| Module | P3 (Pure Mathematics 3) |
| Year | 2016 |
| Session | November |
| Topic | Implicit equations and differentiation |
4 The equation of a curve is \(x y ( x - 6 y ) = 9 a ^ { 3 }\), where \(a\) is a non-zero constant. Show that there is only one point on the curve at which the tangent is parallel to the \(x\)-axis, and find the coordinates of this point.