OCR Further Pure Core 2 2021 November — Question 2

Exam BoardOCR
ModuleFurther Pure Core 2 (Further Pure Core 2)
Year2021
SessionNovember
TopicComplex Numbers Arithmetic
TypeMultiplication and powers of complex numbers

2 In this question you must show detailed reasoning. The complex numbers \(z _ { 1 }\) and \(z _ { 2 }\) are given by \(z _ { 1 } = 3 - 7 \mathrm { i }\) and \(z _ { 2 } = 2 + 4 \mathrm { i }\).
  1. Express each of the following as exact numbers in the form \(a + b \mathrm { i }\).
    1. \(3 z _ { 1 } + 4 z _ { 2 }\)
    2. \(z _ { 1 } z _ { 2 }\)
    3. \(\frac { Z _ { 1 } } { Z _ { 2 } }\)
  2. Write \(z _ { 1 }\) in modulus-argument form giving the modulus in exact form and the argument correct to \(\mathbf { 3 }\) significant figures.