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

Numerical solution of equations — practice question

(a)[2]

By sketching a suitable pair of graphs, show that the equation $2 + e^{-0.2x} = \ln(1 + x)$ has only one root.

(b)[2]

Show by calculation that this root lies between $7$ and $9$.

(c)[3]

Use the iterative formula $x_{n+1} = \exp\left(2 + e^{-0.2x_n}\right) - 1$ to determine the root correct to $2$ decimal places. Record each iteration to $4$ decimal places. [$\exp(x)$ is another notation for $e^x$.]

Worked solution & mark scheme

This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: Sketch a suitable graph, for example $y=2+e^{-0.2x}$, with the correct overall shape.

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