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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 785 · 40 sums
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The method (Split into easy parts): (a + b)² = a² + 2ab + b². (a − b)² = a² − 2ab + b². (a + b)(a − b) = a² − b²; so a² − b² = (a + b)(a − b). a² + b² = (a + b)² − 2ab = (a − b)² + 2ab.

NameDateTime takenScore ___ / 40
  1. 1.Use (a − b)² = a² − 2ab + b² to find 19².
  2. 2.Use a² − b² = (a + b)(a − b) to find 55² − 47².
  3. 3.Use (a + b)² = a² + 2ab + b² to find 105².
  4. 4.Use (a + b)(a − b) = a² − b² to find 104 × 96.
  5. 5.Use a² − b² = (a + b)(a − b) to find 53² − 19².
  6. 6.Find the value of x² − 2xy + y² when x = 6 and y = 4.
  7. 7.If a + b = 11 and ab = 24, what is a² + b²?
  8. 8.Find the value of x² − 2xy + y² when x = 3 and y = 1.
  9. 9.Use (a + b)(a − b) = a² − b² to find 51 × 49.
  10. 10.Use (a − b)² = a² − 2ab + b² to find 53².
  11. 11.Find the value of x² + 2xy + y² when x = 3 and y = 1.
  12. 12.Use (a + b)² = a² + 2ab + b² to find 103².
  13. 13.Use (a + b)² = a² + 2ab + b² to find 31².
  14. 14.Find the value of x² − y² when x = 6 and y = 4.
  15. 15.Use (a − b)² = a² − 2ab + b² to find 21².
  16. 16.Use a² − b² = (a + b)(a − b) to find 31² − 26².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 13².
  18. 18.If a + b = 10 and ab = 9, what is a² + b²?
  19. 19.Find the value of x² − y² when x = 3 and y = 2.
  20. 20.Find the value of x² − 2xy + y² when x = 5 and y = 4.
  21. 21.Find the value of x² + 2xy + y² when x = 11 and y = 6.
  22. 22.Use (a + b)(a − b) = a² − b² to find 55 × 45.
  23. 23.Use (a + b)² = a² + 2ab + b² to find 27².
  24. 24.If a + b = 15 and ab = 56, what is a² + b²?
  25. 25.Find the value of x² + 2xy + y² when x = 7 and y = 6.
  26. 26.Use (a + b)² = a² + 2ab + b² to find 42².
  27. 27.Use (a + b)² = a² + 2ab + b² to find 73².
  28. 28.Use (a − b)² = a² − 2ab + b² to find 59².
  29. 29.Use (a − b)² = a² − 2ab + b² to find 77².
  30. 30.Find the value of x² + 2xy + y² when x = 8 and y = 7.
  31. 31.Find the value of x² + 2xy + y² when x = 15 and y = 1.
  32. 32.Find the value of x² + 2xy + y² when x = 5 and y = 4.
  33. 33.Find the value of x² − 2xy + y² when x = 15 and y = 7.
  34. 34.Find the value of x² + 2xy + y² when x = 5 and y = 3.
  35. 35.Use (a − b)² = a² − 2ab + b² to find 11².
  36. 36.Use a² − b² = (a + b)(a − b) to find 98² − 14².
  37. 37.Find the value of x² − 2xy + y² when x = 12 and y = 11.
  38. 38.Use (a + b)(a − b) = a² − b² to find 52 × 48.
  39. 39.Use (a + b)² = a² + 2ab + b² to find 15².
  40. 40.If a − b = 3 and ab = 88, what is a² + b²?

Answer key

  1. 361
  2. 816
  3. 11025
  4. 9984
  5. 2448
  6. 4
  7. 73
  8. 4
  9. 2499
  10. 2809
  11. 16
  12. 10609
  13. 961
  14. 20
  15. 441
  16. 285
  17. 169
  18. 82
  19. 5
  20. 1
  21. 289
  22. 2475
  23. 729
  24. 113
  25. 169
  26. 1764
  27. 5329
  28. 3481
  29. 5929
  30. 225
  31. 256
  32. 81
  33. 64
  34. 64
  35. 121
  36. 9408
  37. 1
  38. 2496
  39. 225
  40. 185

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