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

Numerical solution of equations — practice question

(i)[3]

By sketching an appropriate pair of graphs, demonstrate that the equation $3\ln x = 15 - x^3$ has exactly one real root.

(ii)[2]

Use calculation to show that the root is between $2.0$ and $2.5$.

(iii)[3]

Apply the iterative formula $x_{n+1} = \sqrt[3]{(15 - 3\ln x_n)}$ to determine the root correct to 3 decimal places. Record each iteration to 5 decimal places.

Worked solution & mark scheme

This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: Accurate sketch shapes for $y=3\ln x$ and $y=15-x^3$

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