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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 277 · 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 a² − b² = (a + b)(a − b) to find 66² − 29².
  2. 2.Find the value of x² − 2xy + y² when x = 6 and y = 5.
  3. 3.Use (a + b)² = a² + 2ab + b² to find 15².
  4. 4.Use (a − b)² = a² − 2ab + b² to find 82².
  5. 5.If a − b = 3 and ab = 18, what is a² + b²?
  6. 6.Use a² − b² = (a + b)(a − b) to find 20² − 19².
  7. 7.Use (a − b)² = a² − 2ab + b² to find 83².
  8. 8.Use (a + b)² = a² + 2ab + b² to find 85².
  9. 9.Use a² − b² = (a + b)(a − b) to find 33² − 24².
  10. 10.Find the value of x² + 2xy + y² when x = 9 and y = 1.
  11. 11.Find the value of x² − y² when x = 7 and y = 1.
  12. 12.Use a² − b² = (a + b)(a − b) to find 25² − 7².
  13. 13.Use (a + b)² = a² + 2ab + b² to find 68².
  14. 14.Find the value of x² + 2xy + y² when x = 10 and y = 6.
  15. 15.Use a² − b² = (a + b)(a − b) to find 86² − 13².
  16. 16.Use (a − b)² = a² − 2ab + b² to find 71².
  17. 17.Use (a + b)(a − b) = a² − b² to find 95 × 85.
  18. 18.Use (a + b)(a − b) = a² − b² to find 83 × 77.
  19. 19.Use (a + b)² = a² + 2ab + b² to find 88².
  20. 20.Use (a + b)(a − b) = a² − b² to find 44 × 36.
  21. 21.Find the value of x² − 2xy + y² when x = 7 and y = 4.
  22. 22.Use a² − b² = (a + b)(a − b) to find 68² − 62².
  23. 23.Find the value of x² − 2xy + y² when x = 6 and y = 3.
  24. 24.Use (a + b)(a − b) = a² − b² to find 23 × 17.
  25. 25.Use (a + b)² = a² + 2ab + b² to find 82².
  26. 26.If a + b = 3 and ab = 2, what is a² + b²?
  27. 27.Use (a + b)² = a² + 2ab + b² to find 26².
  28. 28.Find the value of x² − y² when x = 10 and y = 2.
  29. 29.Use (a + b)(a − b) = a² − b² to find 58 × 42.
  30. 30.Use (a + b)² = a² + 2ab + b² to find 52².
  31. 31.Use a² − b² = (a + b)(a − b) to find 72² − 56².
  32. 32.If a + b = 15 and ab = 56, what is a² + b²?
  33. 33.Use a² − b² = (a + b)(a − b) to find 81² − 51².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 37².
  35. 35.Find the value of x² + 2xy + y² when x = 6 and y = 1.
  36. 36.Find the value of x² − 2xy + y² when x = 14 and y = 4.
  37. 37.Use a² − b² = (a + b)(a − b) to find 97² − 63².
  38. 38.Use a² − b² = (a + b)(a − b) to find 84² − 62².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 45².
  40. 40.Find the value of x² − 2xy + y² when x = 12 and y = 3.

Answer key

  1. 3515
  2. 1
  3. 225
  4. 6724
  5. 45
  6. 39
  7. 6889
  8. 7225
  9. 513
  10. 100
  11. 48
  12. 576
  13. 4624
  14. 256
  15. 7227
  16. 5041
  17. 8075
  18. 6391
  19. 7744
  20. 1584
  21. 9
  22. 780
  23. 9
  24. 391
  25. 6724
  26. 5
  27. 676
  28. 96
  29. 2436
  30. 2704
  31. 2048
  32. 113
  33. 3960
  34. 1369
  35. 49
  36. 100
  37. 5440
  38. 3212
  39. 2025
  40. 81

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