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4MA1/1HR Jun 2020, Question 12: Simultaneous Equations by Elimination

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

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The question, in short

Solve the simultaneous equations 7x + 2y = 5.5 and 3x − 5y = 17, showing clear algebraic working.

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

Solution · 4 marks

  1. 17x + 2y = 5.5
  2. 23x − 5y = 17
  3. 3Multiply first equation by 5: 35x + 10y = 27.5
  4. 4Multiply second equation by 2: 6x − 10y = 34
  5. 5Add the equations: 35x + 10y + 6x − 10y = 27.5 + 34
  6. 641x = 61.5
  7. 7x = 61.5 / 41 = 1.5
  8. 8Substitute x = 1.5 into 7x + 2y = 5.5: 7(1.5) + 2y = 5.5
  9. 910.5 + 2y = 5.5
  10. 102y = 5.5 − 10.5 = −5
  11. 11y = −5 / 2 = −2.5
  12. 12x = 1.5, y = −2.5

Answerx = 1.5, y = −2.5

Stuck on a step? Read the free lesson: Simultaneous Equations by Elimination

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