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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 64 · 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 53².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 93².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 13².
  4. 4.Use (a + b)² = a² + 2ab + b² to find 86².
  5. 5.Use (a + b)² = a² + 2ab + b² to find 74².
  6. 6.Use (a + b)(a − b) = a² − b² to find 62 × 58.
  7. 7.If a − b = 4 and ab = 5, what is a² + b²?
  8. 8.Use a² − b² = (a + b)(a − b) to find 41² − 13².
  9. 9.Use (a − b)² = a² − 2ab + b² to find 59².
  10. 10.Use (a + b)² = a² + 2ab + b² to find 13².
  11. 11.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  12. 12.Use (a + b)² = a² + 2ab + b² to find 67².
  13. 13.Use a² − b² = (a + b)(a − b) to find 46² − 35².
  14. 14.Use (a + b)(a − b) = a² − b² to find 67 × 53.
  15. 15.Use (a + b)² = a² + 2ab + b² to find 29².
  16. 16.Use a² − b² = (a + b)(a − b) to find 75² − 45².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 29².
  18. 18.If a − b = 1 and ab = 12, what is a² + b²?
  19. 19.Use (a + b)(a − b) = a² − b² to find 58 × 42.
  20. 20.Use a² − b² = (a + b)(a − b) to find 93² − 2².
  21. 21.Use a² − b² = (a + b)(a − b) to find 33² − 4².
  22. 22.Use (a − b)² = a² − 2ab + b² to find 42².
  23. 23.Use (a + b)² = a² + 2ab + b² to find 19².
  24. 24.If a + b = 17 and ab = 72, what is a² + b²?
  25. 25.Use (a + b)(a − b) = a² − b² to find 87 × 73.
  26. 26.Use (a − b)² = a² − 2ab + b² to find 23².
  27. 27.If a − b = 8 and ab = 33, what is a² + b²?
  28. 28.If a + b = 13 and ab = 22, what is a² + b²?
  29. 29.Find the value of x² − 2xy + y² when x = 8 and y = 7.
  30. 30.Use (a + b)(a − b) = a² − b² to find 106 × 94.
  31. 31.Find the value of x² − 2xy + y² when x = 4 and y = 3.
  32. 32.Use a² − b² = (a + b)(a − b) to find 68² − 39².
  33. 33.Use (a + b)(a − b) = a² − b² to find 109 × 91.
  34. 34.If a − b = 2 and ab = 3, what is a² + b²?
  35. 35.Use (a − b)² = a² − 2ab + b² to find 66².
  36. 36.Find the value of x² − y² when x = 3 and y = 2.
  37. 37.Use (a − b)² = a² − 2ab + b² to find 49².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 15².
  39. 39.Use (a − b)² = a² − 2ab + b² to find 62².
  40. 40.Find the value of x² − 2xy + y² when x = 8 and y = 3.

Answer key

  1. 2809
  2. 8649
  3. 169
  4. 7396
  5. 5476
  6. 3596
  7. 26
  8. 1512
  9. 3481
  10. 169
  11. 899
  12. 4489
  13. 891
  14. 3551
  15. 841
  16. 3600
  17. 841
  18. 25
  19. 2436
  20. 8645
  21. 1073
  22. 1764
  23. 361
  24. 145
  25. 6351
  26. 529
  27. 130
  28. 125
  29. 1
  30. 9964
  31. 1
  32. 3103
  33. 9919
  34. 10
  35. 4356
  36. 5
  37. 2401
  38. 225
  39. 3844
  40. 25

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