Mathematics 9709 · AS & A Level · Numerical solution of equations

Numerical solution of equations — practice question

The diagram illustrates a section of the curve whose equation is $y = x^3 \cos 2x$. This curve reaches a maximum at the point $M$.
(a)[3]

Show that the $x$-coordinate of $M$ satisfies the equation $x = \sqrt[3]{1.5x^2 \cot 2x}$.

(b)[2]

Apply the equation in part (a) and, by calculation, show that the $x$-coordinate of $M$ lies between $0.59$ and $0.60$.

(c)[3]

Use iteration, based on the equation in part (a), to determine the $x$-coordinate of $M$ correct to $3$ significant figures. Give each iteration result to $5$ significant figures.

Worked solution & mark scheme

This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: Differentiate using the product rule to reach $ax^2\cos 2x-bx^3\sin 2x$

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