Mathematics 9709 · AS & A Level · Complex numbers

Complex numbers — practice question

(a)[6]

It is given that $(1 + 3i)w = 2 + 4i$. Show all the working needed to prove that the exact value of $|w^2|$ equals $2$ and determine $\arg(w^2)$ correct to $3$ significant figures.

(b)[4]

On one Argand diagram, sketch the loci $|z| = 5$ and $|z - 5| = |z|$. Hence determine the complex numbers at the points shared by both loci, with each answer written in the form $re^{i\theta}$.

Worked solution & mark scheme

This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: Find $w$ by using the conjugate of $1+3i$

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