N2017 P1 Q8

N2017 P1 Q8

10 marks
Past Year National Exams
Free

Do not use a calculator in answering this question.

  1. Find the roots of the equation \({{z}^{2}}\left( 1-\mathbf{i} \right)-2z+\left( 5+5\,\mathbf{i} \right)=0\), giving your answers in cartesian form \(a+\mathbf{i}\,b\).[3]
    1. Given that \(\omega =1-\mathbf{i}\), find \({{\omega }^{2}}\), \({{\omega }^{3}}\) and \({{\omega }^{4}}\) in cartesian form. Given also that \({{\omega }^{4}}+p{{\omega }^{3}}+39{{\omega }^{2}}+q\omega +58=0\),where \(p\) and \(q\) are real, find \(p\) and \(q\).[4]
    2. Using the values of \(p\) and \(q\) in part (b)(i), express \({{\omega }^{4}}+p{{\omega }^{3}}+39{{\omega }^{2}}+q\omega +58\) as the product of two quadratic factors.[3]

Video Solution:

Default solution

Timothy Gan
  1. List item image
    List item image
    1. Sub-item image
      Sub-item image
    2. Sub-item image
      Sub-item image
Answer:(a) \(z=-1+2\mathrm{i}\) or \(z=2-\mathrm{i}\) (b)(i) \(\omega^2=-2\mathrm{i}\), \(\omega^3=-2-2\mathrm{i}\), \(\omega^4=-4\), \(p=-6\), \(q=-66\) (b)(ii) \((\omega^2-2\omega+2)(\omega^2-4\omega+29)\)

Need help? Join our JC Math tuition classes.

Learn more