Mathematics 9709 · AS & A Level · Complex numbers

Complex numbers — practice question

(a)[3]

Verify that $-1 + \sqrt{5}i$ satisfies the equation $2x^3 + x^2 + 6x - 18 = 0$.

(b)[4]

Find the remaining roots of this equation.

Worked solution & mark scheme

This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Substitute $-1+\sqrt{5}i$ and carry out the expansions” …

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