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

Numerical solution of equations — practice question

(i)[2]

By drawing an appropriate pair of graphs, show that the equation $\ln x = 4 - \frac{1}{2}x$ has exactly one real root, $\alpha$.

(ii)[2]

Verify by calculation that the root satisfies $4.5 < \alpha < 5.0$.

(iii)[3]

Apply the iterative formula $x_{n+1} = 8 - 2\ln x_n$ to determine $\alpha$ correct to 2 decimal places, and state every iterate to 4 decimal places.

Worked solution & mark scheme

This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: Produce a clear sketch of $y=\ln x$

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