Mathematics 9709 · AS & A Level · Complex numbers

Complex numbers — practice question

You are told that $z = -\sqrt{3} + i$.
(a)[3]

Write $z^2$ in the form $re^{i\theta}$, with $r > 0$ and $-\pi < \theta \leq \pi$.

(b)[3]

The complex number $\omega$ satisfies $z^2\,\omega$ being real and $\left|\frac{z^2}{\omega}\right| = 12$. Determine the two possible values of $\omega$, with answers written in the form $Re^{i\alpha}$, where $R > 0$ and $-\pi < \alpha \leq \pi$.

Worked solution & mark scheme

This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: Find $r=4$

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