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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 347 · 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 67².
  2. 2.Find the value of x² + 2xy + y² when x = 7 and y = 2.
  3. 3.Use (a + b)² = a² + 2ab + b² to find 42².
  4. 4.If a + b = 13 and ab = 30, what is a² + b²?
  5. 5.Use a² − b² = (a + b)(a − b) to find 54² − 47².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 92².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 93².
  8. 8.Use (a + b)² = a² + 2ab + b² to find 96².
  9. 9.Use (a − b)² = a² − 2ab + b² to find 55².
  10. 10.Use a² − b² = (a + b)(a − b) to find 30² − 9².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 58².
  12. 12.Find the value of x² + 2xy + y² when x = 8 and y = 3.
  13. 13.Use (a + b)(a − b) = a² − b² to find 77 × 63.
  14. 14.Use (a + b)(a − b) = a² − b² to find 58 × 42.
  15. 15.Use (a − b)² = a² − 2ab + b² to find 77².
  16. 16.Find the value of x² − 2xy + y² when x = 3 and y = 2.
  17. 17.Use (a − b)² = a² − 2ab + b² to find 19².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 65².
  19. 19.Use (a − b)² = a² − 2ab + b² to find 36².
  20. 20.Use (a + b)(a − b) = a² − b² to find 68 × 52.
  21. 21.Use (a + b)² = a² + 2ab + b² to find 85².
  22. 22.Use a² − b² = (a + b)(a − b) to find 92² − 28².
  23. 23.Use (a + b)² = a² + 2ab + b² to find 15².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 22².
  25. 25.Use a² − b² = (a + b)(a − b) to find 98² − 35².
  26. 26.Find the value of x² − y² when x = 6 and y = 4.
  27. 27.Use (a + b)² = a² + 2ab + b² to find 72².
  28. 28.Use (a − b)² = a² − 2ab + b² to find 51².
  29. 29.Use (a + b)(a − b) = a² − b² to find 105 × 95.
  30. 30.Use (a + b)(a − b) = a² − b² to find 83 × 77.
  31. 31.Use (a + b)(a − b) = a² − b² to find 36 × 24.
  32. 32.Use (a + b)(a − b) = a² − b² to find 42 × 38.
  33. 33.If a − b = 1 and ab = 20, what is a² + b²?
  34. 34.Use (a + b)² = a² + 2ab + b² to find 47².
  35. 35.Use a² − b² = (a + b)(a − b) to find 81² − 2².
  36. 36.Find the value of x² − 2xy + y² when x = 3 and y = 1.
  37. 37.Use a² − b² = (a + b)(a − b) to find 43² − 2².
  38. 38.If a + b = 3 and ab = 2, what is a² + b²?
  39. 39.Use a² − b² = (a + b)(a − b) to find 54² − 17².
  40. 40.Use a² − b² = (a + b)(a − b) to find 34² − 2².

Answer key

  1. 4489
  2. 81
  3. 1764
  4. 109
  5. 707
  6. 8464
  7. 8649
  8. 9216
  9. 3025
  10. 819
  11. 3364
  12. 121
  13. 4851
  14. 2436
  15. 5929
  16. 1
  17. 361
  18. 4225
  19. 1296
  20. 3536
  21. 7225
  22. 7680
  23. 225
  24. 484
  25. 8379
  26. 20
  27. 5184
  28. 2601
  29. 9975
  30. 6391
  31. 864
  32. 1596
  33. 41
  34. 2209
  35. 6557
  36. 4
  37. 1845
  38. 5
  39. 2627
  40. 1152

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