Mathematics 9709 · AS & A Level · Complex numbers

Complex numbers — practice question

The polynomial $p(z)$ is given by $p(z) = z^3 + mz^2 + 24z + 32$, with $m$ a constant. You are told that $(z + 2)$ divides $p(z)$.
(i)[2]

Determine $m$.

(ii(a))[5]

Therefore, showing all of your working, determine the three roots of the equation $p(z) = 0$.

(ii(b))[6]

Hence, showing all of your working, find the six roots of the equation $p(z^2) = 0$.

Worked solution & mark scheme

This 13-mark question has a full step-by-step worked solution and mark scheme. One marking point: Use $p(-2)=0$, or an equivalent condition, to work out $m$.

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