Mathematics 9709 · AS & A Level · Complex numbers

Complex numbers — practice question

(a)[3]

The complex number $\frac{3 - 5i}{1 + 4i}$ is labelled $u$. Show your working and express $u$ in the form $x + iy$, where $x$ and $y$ are real.

(b(i))[4]

On a sketch of an Argand diagram, shade the set of points representing complex numbers that satisfy the inequalities $|z - 2 - i| \leq 1$ and $|z - i| \leq |z - 2|$.

(b(ii))[2]

Calculate the maximum value of $\arg z$ for points in the shaded region.

Worked solution & mark scheme

This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: Multiply the numerator and denominator by $1-4i$ (or an equivalent factor) and use $i^2=-1$, or use equations in $x$ and $y$

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