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4MA1/2HR Jan 2020, Question 1: Prime Factorization

Pearson Edexcel International GCSE Mathematics A 4MA1 · Paper 2HR (Higher) · Calculator · 3 marks

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The question, in short

Two index and factor questions: combine powers of 5 into one, and express 800 as a product of primes with working shown.

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Part (a) · 1 mark

Give the result of multiplying 5 to the power 17 by 5 squared, as one power of 5.

  1. 1Same base, so add the powers: 17 + 2 = 19
  2. 25¹⁷ × 5² = 5¹⁹

Answer5¹⁹

Part (b) · 2 marks

Break 800 down into prime factors, displaying the method used to reach the factorisation.

  1. 1Divide by 2 again and again: 800, 400, 200, 100, 50, 25
  2. 2That uses five 2s and leaves 25
  3. 325 = 5 × 5
  4. 4800 = 2×2×2×2×2×5×5

Answer2×2×2×2×2×5×5

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