Mathematics 9709 · AS & A Level · Complex numbers

Complex numbers — practice question

(a)[5]

The complex number $w$ has $\Re w > 0$ and satisfies $w + 3w^* = iw^2$, where $w^*$ is the complex conjugate of $w$. Find $w$, giving the answer in the form $x + iy$, where $x$ and $y$ are real.

(b)[6]

On a sketch of an Argand diagram, shade the set of points for complex numbers $z$ that satisfy both $|z - 2i| \leq 2$ and $0 \leq \arg(z + 2i) \leq \tfrac{1}{4}\pi$. Calculate the greatest value of $|z|$ for points in this set, and give your answer correct to 2 decimal places.

Worked solution & mark scheme

This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: Substitute $w=x+iy$ and state a valid equation in $x$ and $y$

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