4MA1/2HR Jun 2018, Question 14: Exponential Equations
Pearson Edexcel International GCSE Mathematics A 4MA1 · Paper 2HR (Higher) · Calculator · 3 marks
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The question, in short
Solve 128 = 4²ˣ × 2ˣ for the value of x, using powers of 2.
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Solution · 3 marks
- 1Write everything as powers of 2: 128 = 2⁷ and 4 = 2²
- 24²ˣ × 2ˣ = 2⁴ˣ × 2ˣ = 2⁵ˣ
- 3So 2⁷ = 2⁵ˣ, giving 5x = 7
- 4x = 7 ÷ 5 = 1.4
Answer1.4
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