Question 4 - A-Level Maths

4 For each of the following curves, find the exact gradient at the point indicated:

\(y = 3 \cos 2 x - 5 \sin x\) at \(\left( \frac { 1 } { 6 } \pi , - 1 \right)\),
\(x ^ { 3 } + 6 x y + y ^ { 3 } = 21\) at \(( 1,2 )\).