0580/21 Oct/Nov 2025, Question 19: Solving Linear Equations
Cambridge IGCSE Mathematics 0580 · Paper 21 (Extended) · Non-calculator · 3 marks
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The question, in short
Solve the equation (1/3)ˣ = 9^(x + 4) for x.
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Solution · 3 marks
- 1(1/3)ˣ = (3⁻¹)ˣ = 3⁻ˣ and 9^(x + 4) = 3^(2(x + 4))
- 2−x = 2(x + 4) = 2x + 8
- 3−3x = 8
- 4x = −8/3 = −2 2/3
Answer−8/3 or −2 2/3
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