Exam-Style Problems

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Nov 2012 p33 q10
1995

(a) Without using a calculator, solve the equation \(iw^2 = (2 - 2i)^2\).

(b) (i) Sketch an Argand diagram showing the region \(R\) consisting of points representing the complex numbers \(z\) where \(|z - 4 - 4i| \leq 2\).

(ii) For the complex numbers represented by points in the region \(R\), it is given that \(p \leq |z| \leq q\) and \(\alpha \leq \arg z \leq \beta\). Find the values of \(p, q, \alpha\) and \(\beta\), giving your answers correct to 3 significant figures.

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Nov 2012 p31 q9
1996

The complex number \(1 + (\sqrt{2})i\) is denoted by \(u\). The polynomial \(x^4 + x^2 + 2x + 6\) is denoted by \(p(x)\).

  1. Showing your working, verify that \(u\) is a root of the equation \(p(x) = 0\), and write down a second complex root of the equation. [4]
  2. Find the other two roots of the equation \(p(x) = 0\). [6]
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June 2012 p33 q10
1997

(a) The complex numbers u and w satisfy the equations

\(u - w = 4i\) and \(uw = 5\).

Solve the equations for u and w, giving all answers in the form x + iy, where x and y are real.

(b) (i) On a sketch of an Argand diagram, shade the region whose points represent complex numbers satisfying the inequalities \(|z - 2 + 2i| \leq 2\), \(\text{arg } z \leq -\frac{1}{4}\pi\) and \(\text{Re } z \geq 1\), where \(\text{Re } z\) denotes the real part of z.

(ii) Calculate the greatest possible value of \(\text{Re } z\) for points lying in the shaded region.

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June 2012 p32 q7
1998

The complex number u is defined by

\(u = \frac{1 + 2i}{1 - 3i}\).

  1. Express u in the form x + iy, where x and y are real. [3]
  2. Show on a sketch of an Argand diagram the points A, B and C representing the complex numbers u, 1 + 2i and 1 - 3i respectively. [2]
  3. By considering the arguments of 1 + 2i and 1 - 3i, show that \(\arctan 2 + \arctan 3 = \frac{3}{4} \pi\). [3]
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June 2012 p31 q4
1999

The complex number u is defined by \(u = \frac{(1 + 2i)^2}{2 + i}\).

  1. Without using a calculator and showing your working, express u in the form x + iy, where x and y are real.
  2. Sketch an Argand diagram showing the locus of the complex number z such that \(|z-u| = |u|\).
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