0580/42 Oct/Nov 2025, Question 21: Proportion to Powers of x
Cambridge IGCSE Mathematics 0580 · Paper 42 (Extended) · Calculator · 4 marks
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The question, in short
Given y inversely proportional to (x + 2)² and w proportional to x, with y = 8 when x = 3.5 and w = 15 when x = 90, express y in terms of w.
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Solution · 4 marks
- 1y = k/(x + 2)²: 8 = k/(3.5 + 2)², so k = 8 × 5.5² = 242
- 2w = cx: 15 = 90c, so c = 1/6 and w = x/6
- 3x = 6w
- 4y = 242/(6w + 2)²
Answery = 242/(6w + 2)²
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Also searched as: 0580/42/O/N/25 · 0580_w25_qp_42 · 0580 w25 42 · question 21.
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