2022 TMJC P1 Q9

2022 TMJC P1 Q9

12 marks
Prelims
  1. The complex number \(z\) is given by \(z=x+y\mathbf{i}\), where \(x\) and \(y\) are non-zero real numbers. Given that \(\left| z \right|=1\), find the possible values of \(z\) for which \(\frac{{{\left( {{z}^{2}} \right)}^{*}}}{z}\) is real.[6]
  2. Without the use of a calculator, find the roots of the equation \({{z}^{2}}=33+56\mathbf{i}\), expressing your answer in cartesian form \(x+\mathbf{i}y\) where \(x\) and \(y\) are real.[4]
    Hence, find in cartesian form, the roots of the equation \({{w}^{2}}=-33+56\mathbf{i}\).[2]

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Answer:(a) z = -1/2 ± (√3/2)i; (b) z = 7+4i or -7-4i; w = 4+7i or -4-7i

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