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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 611 · 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 77².
  2. 2.Use (a + b)(a − b) = a² − b² to find 101 × 99.
  3. 3.Use a² − b² = (a + b)(a − b) to find 73² − 29².
  4. 4.If a − b = 1 and ab = 12, what is a² + b²?
  5. 5.Use (a + b)² = a² + 2ab + b² to find 42².
  6. 6.Use (a + b)² = a² + 2ab + b² to find 76².
  7. 7.Find the value of x² − y² when x = 3 and y = 1.
  8. 8.Use (a + b)(a − b) = a² − b² to find 41 × 39.
  9. 9.Use a² − b² = (a + b)(a − b) to find 73² − 63².
  10. 10.If a − b = 2 and ab = 15, what is a² + b²?
  11. 11.Find the value of x² − y² when x = 8 and y = 3.
  12. 12.Use (a + b)² = a² + 2ab + b² to find 11².
  13. 13.If a + b = 18 and ab = 80, what is a² + b²?
  14. 14.Use a² − b² = (a + b)(a − b) to find 95² − 77².
  15. 15.Use a² − b² = (a + b)(a − b) to find 68² − 34².
  16. 16.Use a² − b² = (a + b)(a − b) to find 22² − 20².
  17. 17.Find the value of x² + 2xy + y² when x = 11 and y = 1.
  18. 18.Find the value of x² − y² when x = 14 and y = 12.
  19. 19.Use a² − b² = (a + b)(a − b) to find 52² − 14².
  20. 20.Use (a + b)² = a² + 2ab + b² to find 32².
  21. 21.Use (a + b)² = a² + 2ab + b² to find 41².
  22. 22.Use a² − b² = (a + b)(a − b) to find 50² − 45².
  23. 23.Use (a + b)² = a² + 2ab + b² to find 66².
  24. 24.Use (a + b)(a − b) = a² − b² to find 36 × 24.
  25. 25.Use (a − b)² = a² − 2ab + b² to find 27².
  26. 26.Use (a + b)(a − b) = a² − b² to find 78 × 62.
  27. 27.Use (a − b)² = a² − 2ab + b² to find 66².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 33².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 99².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 12².
  31. 31.Find the value of x² − 2xy + y² when x = 10 and y = 5.
  32. 32.Use a² − b² = (a + b)(a − b) to find 43² − 22².
  33. 33.Use (a − b)² = a² − 2ab + b² to find 11².
  34. 34.Use a² − b² = (a + b)(a − b) to find 38² − 4².
  35. 35.Use a² − b² = (a + b)(a − b) to find 65² − 46².
  36. 36.Use a² − b² = (a + b)(a − b) to find 69² − 59².
  37. 37.Use (a + b)² = a² + 2ab + b² to find 35².
  38. 38.Use a² − b² = (a + b)(a − b) to find 63² − 25².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 21².
  40. 40.Use a² − b² = (a + b)(a − b) to find 69² − 44².

Answer key

  1. 5929
  2. 9999
  3. 4488
  4. 25
  5. 1764
  6. 5776
  7. 8
  8. 1599
  9. 1360
  10. 34
  11. 55
  12. 121
  13. 164
  14. 3096
  15. 3468
  16. 84
  17. 144
  18. 52
  19. 2508
  20. 1024
  21. 1681
  22. 475
  23. 4356
  24. 864
  25. 729
  26. 4836
  27. 4356
  28. 1089
  29. 9801
  30. 144
  31. 25
  32. 1365
  33. 121
  34. 1428
  35. 2109
  36. 1280
  37. 1225
  38. 3344
  39. 441
  40. 2825

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