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

Numerical solution of equations — practice question

The diagram illustrates the curve given by $y = \frac{3x + 2}{\ln x}$. This curve has a minimum point $M$.
(a)[3]

Find an expression for $\frac{dy}{dx}$ and show that the $x$-coordinate of $M$ satisfies the equation $x = \frac{3x + 2}{3 \ln x}$.

(b)[2]

Use the equation from part (a) to demonstrate by calculation that the $x$-coordinate of $M$ lies between $3$ and $4$.

(c)[3]

Use an iterative formula, based on the equation in part (a), to determine the $x$-coordinate of $M$ correct to $5$ significant figures. Give each iteration result to $7$ significant figures.

Worked solution & mark scheme

This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: Apply quotient rule (or an equivalent method) to obtain the first derivative

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