N2009 P1 Q9

N2009 P1 Q9

Junior College 2
12 marks
  1. Solve the equation \(z^7-(1+\mathrm i)=0\), giving the roots in the form \(r\mathrm e^{\mathrm i\alpha}\), where \(r>0\) and \(-\pi<\alpha\leq\pi\).[5]
  2. Show the roots on an Argand diagram.[2]
  3. The roots represented by \(z_1\) and \(z_2\) are such that \(0<\arg(z_1)<\arg(z_2)<\frac12\pi\). Explain why the locus of all points \(z\) such that \(|z-z_1|=|z-z_2|\) passes through the origin. Draw this locus on your Argand diagram and find its exact cartesian equation.[5]

Solution:

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Finding similar questions...
Answer:(i) \(2^{1/14}\mathrm e^{\mathrm ik\pi/28}\), \(k=-23,-15,-7,1,9,17,25\). (iii) \(y=x\tan(5\pi/28)\).

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