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

Numerical solution of equations — practice question

The graph given by $y = x\ln(4x + 1) - 3x$ has a single stationary point, $P$.
(a)[4]

Demonstrate that the $x$-coordinate of $P$ satisfies $x = \frac{2x + 0.75}{\ln(4x + 1)} - 0.25$.

(b)[2]

Use calculation to show that the $x$-coordinate of $P$ is between $1.8$ and $1.9$.

(c)[3]

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

Worked solution & mark scheme

This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: Try applying the product rule when differentiating $x\ln(4x+1)$

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