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4024/13 May/Jun 2026, Question 21: Exponential Equations

Cambridge O Level Mathematics 4024 · Paper 13 (Non-calculator) · Non-calculator · 5 marks

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The question, in short

Simplify a power expression with a negative fractional index, then solve an exponential equation for x.

Summarised in our own words. Use the official paper for the exact wording and any diagrams.

Part (a) · 2 marks

Simplify (25 ÷ x⁴) raised to the power −3/2, giving the result in simplest form.

  1. 1(25/x⁴)^(−3/2) = (x⁴/25)^(3/2)
  2. 2√(x⁴/25) = x²/5
  3. 3(x²/5)³ = x⁶/125

Answerx⁶/125

Part (b) · 3 marks

Find the value of x satisfying 8ˣ = 4ˣ⁺³.

  1. 18ˣ = 2³ˣ and 4ˣ⁺³ = 2²⁽ˣ⁺³⁾ = 2²ˣ⁺⁶
  2. 23x = 2x + 6
  3. 3x = 6

Answer6

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