Mathematics 9709 · AS & A Level · Differentiation

Differentiation — practice question

The curve $y = f(x)$ passes through the stationary point $P(3, -10)$. It is also stated that $f'(x) = 2x^2 + kx - 12$, with $k$ as a constant.
(i)[4]

Show that $k = -2$ and then determine the $x$-coordinate of the other stationary point, $Q$.

(ii)[2]

Find $f''(x)$ and work out the nature of the stationary points $P$ and $Q$.

(iii)[4]

Find the function $f(x)$.

Worked solution & mark scheme

This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: Differentiate to get $f'(x)=18+3x-12$, then set this equal to zero

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