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

Numerical solution of equations — practice question

(i)[2]

By sketching an appropriate pair of graphs, show that the equation $\cot x = 4x - 2$, where $x$ is in radians, has a single root for $0 \leq x \leq \frac{\pi}{2}$.

(ii)[2]

Verify by calculation that this root is between $x = 0.7$ and $x = 0.9$.

(iii)[1]

Show that this root also satisfies the equation $x = \frac{1 + 2\tan x}{4\tan x}$.

(iv)[3]

Use the iterative formula $x_{n+1} = \frac{1 + 2\tan x_n}{4\tan x_n}$ to determine this root correct to $2$ decimal places. Give the value of each iteration to $4$ decimal places.

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