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

Numerical solution of equations — practice question

(i)[2]

Using a suitable pair of sketches, demonstrate that the equation $3e^x = 8 - 2x$ has a single root.

(ii)[2]

Confirm by calculation that this root is between $x = 0.7$ and $x = 0.8$.

(iii)[1]

Demonstrate that this root also meets the equation $x = \ln\left(\frac{8 - 2x}{3}\right)$.

(iv)[3]

Use the iterative formula $x_{n+1} = \ln\left(\frac{8 - 2x_n}{3}\right)$ to find this 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: Produce a recognisable sketch of an appropriate graph, for example $y=3e^x$ or $y=8-2x$

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