- (a) Factorise completely \(9 x - 4 x ^ { 3 }\)
(b) Sketch the curve \(C\) with equation
$$y = 9 x - 4 x ^ { 3 }$$
Show on your sketch the coordinates at which the curve meets the \(x\)-axis.
The points \(A\) and \(B\) lie on \(C\) and have \(x\) coordinates of - 2 and 1 respectively.
(c) Show that the length of \(A B\) is \(k \sqrt { } 10\) where \(k\) is a constant to be found.