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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 985 · 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)(a − b) = a² − b² to find 103 × 97.
  2. 2.Use a² − b² = (a + b)(a − b) to find 64² − 50².
  3. 3.If a + b = 9 and ab = 14, what is a² + b²?
  4. 4.If a + b = 5 and ab = 6, what is a² + b²?
  5. 5.Use (a + b)² = a² + 2ab + b² to find 101².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 96².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 83².
  8. 8.Use (a + b)² = a² + 2ab + b² to find 45².
  9. 9.Use (a − b)² = a² − 2ab + b² to find 66².
  10. 10.If a − b = 2 and ab = 8, what is a² + b²?
  11. 11.Use (a − b)² = a² − 2ab + b² to find 73².
  12. 12.Find the value of x² − 2xy + y² when x = 14 and y = 1.
  13. 13.Use a² − b² = (a + b)(a − b) to find 70² − 21².
  14. 14.Use (a + b)² = a² + 2ab + b² to find 39².
  15. 15.Use a² − b² = (a + b)(a − b) to find 52² − 46².
  16. 16.Use a² − b² = (a + b)(a − b) to find 88² − 36².
  17. 17.Find the value of x² − y² when x = 11 and y = 1.
  18. 18.Find the value of x² − 2xy + y² when x = 6 and y = 2.
  19. 19.Use a² − b² = (a + b)(a − b) to find 47² − 3².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 55².
  21. 21.If a − b = 5 and ab = 24, what is a² + b²?
  22. 22.Use (a − b)² = a² − 2ab + b² to find 11².
  23. 23.Use (a + b)(a − b) = a² − b² to find 76 × 64.
  24. 24.Use (a + b)² = a² + 2ab + b² to find 21².
  25. 25.If a − b = 4 and ab = 5, what is a² + b²?
  26. 26.Find the value of x² + 2xy + y² when x = 8 and y = 7.
  27. 27.Use (a − b)² = a² − 2ab + b² to find 57².
  28. 28.Use (a + b)(a − b) = a² − b² to find 72 × 68.
  29. 29.Find the value of x² + 2xy + y² when x = 4 and y = 2.
  30. 30.Use a² − b² = (a + b)(a − b) to find 63² − 43².
  31. 31.Use (a − b)² = a² − 2ab + b² to find 52².
  32. 32.Use a² − b² = (a + b)(a − b) to find 54² − 20².
  33. 33.Find the value of x² − y² when x = 15 and y = 11.
  34. 34.Use (a + b)² = a² + 2ab + b² to find 15².
  35. 35.Find the value of x² + 2xy + y² when x = 10 and y = 6.
  36. 36.Use (a − b)² = a² − 2ab + b² to find 36².
  37. 37.If a + b = 7 and ab = 6, what is a² + b²?
  38. 38.Use (a + b)(a − b) = a² − b² to find 23 × 17.
  39. 39.Use a² − b² = (a + b)(a − b) to find 27² − 19².
  40. 40.Use (a − b)² = a² − 2ab + b² to find 14².

Answer key

  1. 9991
  2. 1596
  3. 53
  4. 13
  5. 10201
  6. 9216
  7. 6889
  8. 2025
  9. 4356
  10. 20
  11. 5329
  12. 169
  13. 4459
  14. 1521
  15. 588
  16. 6448
  17. 120
  18. 16
  19. 2200
  20. 3025
  21. 73
  22. 121
  23. 4864
  24. 441
  25. 26
  26. 225
  27. 3249
  28. 4896
  29. 36
  30. 2120
  31. 2704
  32. 2516
  33. 104
  34. 225
  35. 256
  36. 1296
  37. 37
  38. 391
  39. 368
  40. 196

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