\(The complex number w is defined by w = 2 + i.\)
(i) Showing your working, express w2 in the form x + iy, where x and y are real. Find the modulus of w2.
(ii) Shade on an Argand diagram the region whose points represent the complex numbers z which satisfy \(|z - w^2| \leq |w^2|\).
Solution
(i) To find w2, calculate \((2 + i)^2\):
\((2 + i)^2 = 2^2 + 2 \cdot 2 \cdot i + i^2 = 4 + 4i + i^2\).
Since \(i^2 = -1\), this becomes \(4 + 4i - 1 = 3 + 4i\).
The modulus of w2 is \(|3 + 4i| = \sqrt{3^2 + 4^2} = \sqrt{9 + 16} = \sqrt{25} = 5\).
(ii) On an Argand diagram, the region is a circle centered at \((3, 4)\) with radius 5, representing the inequality \(|z - w^2| \leq |w^2|\).
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