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0580/22 Oct/Nov 2021, Question 18: Simultaneous Equations by Elimination

Cambridge IGCSE Mathematics 0580 · Paper 22 (Extended) · Calculator · 5 marks

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The question, in short

Solve the simultaneous equations y = x² − 9x + 21 and y = 2x − 3, showing all working.

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

Solution · 5 marks

  1. 1x² − 9x + 21 = 2x − 3
  2. 2x² − 11x + 24 = 0
  3. 3(x − 3)(x − 8) = 0
  4. 4x = 3 or x = 8
  5. 5y = 2 × 3 − 3 = 3 and y = 2 × 8 − 3 = 13
  6. 6x = 3, y = 3 and x = 8, y = 13

Answerx = 3, y = 3 and x = 8, y = 13

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Also searched as: 0580/22/O/N/21 · 0580_w21_qp_22 · 0580 w21 22 · question 18.
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