Complex Numbers - Modulus, Argument, and Operations on Complex Numbers

Complex Numbers - Modulus, Argument, and Operations on Complex Numbers

6 marks

Do not use a calculator in answering this question.

  1. Find the roots of the equation \(x^2(1+\mathrm{i})-4x+(4-4\mathrm{i})=0\), giving your answers in cartesian form \(a+\mathrm{i}b\).[3]
  2. The complex numbers \(z\) and \(w\) are such that \(z=1+\mathrm{i}\) and \(w=-1-\mathrm{i}\sqrt{3}\). Find the modulus and argument of \(\frac{z}{w^*}\) exactly.[3]

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Answer:(a) \(x=2\) or \(x=-2i\) (b) \(\left|\frac{z}{w^*}\right|=\frac{\sqrt2}{2}\), \(\arg\left(\frac{z}{w^*}\right)=-\frac{5\pi}{12}\)

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