Unit 1: Number and Algebra

Topic 1.12: Complex numbers: intro (HL only) Questions

Practice 11 exam-style questions for IB Math AI SL Topic 1.12. Review the question stems below, then unlock the full Question Bank to access markschemes, model answers, and AI grading.

1Find2 marks
2026
Find the value of |6 + 8i|.
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21 mark
2026
The conjugate of z = −3 − 7i is:
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31 mark
2026
i³ simplifies to:
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41 mark
2026
(2 + i)(2 − i) equals:
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51 mark
2026
On an Argand diagram, the point (−2, 3) represents:
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6Find2 marks
2026
Given z₁ = 4 − 3i and z₂ = −1 + 2i, find z₁ + z₂ and z₁ − z₂.
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71 mark
2026
If |z| = 0, then z must be:
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8Express2 marks
2026
Express (2 + 3i)² in the form a + bi.
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9Express3 marks
2026
Express (3 + i)/(1 − 2i) in the form a + bi.
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10Find3 marks
2026
z = 2 − 5i. Plot z on an Argand diagram and find |z|, giving the answer to 3 s.f.
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11Find3 marks
2026
A signal is z = (4 + 2i)(1 + 3i). Write z in the form a + bi and find its amplitude |z| to 3 s.f.
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