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4MA1/1H Jun 2021, Question 17: Expand and Simplify

Pearson Edexcel International GCSE Mathematics A 4MA1 · Paper 1H (Higher) · Calculator · 3 marks

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The question, in short

Using algebra, prove that for any 3 consecutive even numbers, the largest squared minus the smallest squared equals 8 times the middle number.

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Solution · 3 marks

  1. 1Let the three consecutive even numbers be 2n, 2n + 2, 2n + 4
  2. 2(2n + 4)² − (2n)² = (4n² + 16n + 16) − 4n² = 16n + 16
  3. 38 times the middle number = 8(2n + 2) = 16n + 16
  4. 4Since both expressions are equal, the statement is proven

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