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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 867 · 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 97² − 66².
  2. 2.Use (a − b)² = a² − 2ab + b² to find 88².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 52².
  4. 4.If a + b = 10 and ab = 24, what is a² + b²?
  5. 5.Use (a + b)² = a² + 2ab + b² to find 26².
  6. 6.Use (a + b)² = a² + 2ab + b² to find 93².
  7. 7.Use (a + b)(a − b) = a² − b² to find 87 × 73.
  8. 8.Use (a − b)² = a² − 2ab + b² to find 17².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 17².
  10. 10.If a − b = 2 and ab = 120, what is a² + b²?
  11. 11.Use a² − b² = (a + b)(a − b) to find 98² − 57².
  12. 12.Use a² − b² = (a + b)(a − b) to find 33² − 9².
  13. 13.Use (a + b)² = a² + 2ab + b² to find 22².
  14. 14.If a + b = 11 and ab = 10, what is a² + b²?
  15. 15.Use (a − b)² = a² − 2ab + b² to find 84².
  16. 16.If a − b = 7 and ab = 60, what is a² + b²?
  17. 17.Use (a + b)(a − b) = a² − b² to find 46 × 34.
  18. 18.Use (a − b)² = a² − 2ab + b² to find 32².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 38².
  20. 20.If a − b = 3 and ab = 40, what is a² + b²?
  21. 21.Find the value of x² + 2xy + y² when x = 10 and y = 3.
  22. 22.Use (a − b)² = a² − 2ab + b² to find 67².
  23. 23.Find the value of x² − 2xy + y² when x = 5 and y = 3.
  24. 24.Use (a − b)² = a² − 2ab + b² to find 87².
  25. 25.Use (a − b)² = a² − 2ab + b² to find 28².
  26. 26.Use a² − b² = (a + b)(a − b) to find 93² − 22².
  27. 27.Find the value of x² + 2xy + y² when x = 11 and y = 8.
  28. 28.If a − b = 5 and ab = 36, what is a² + b²?
  29. 29.Find the value of x² + 2xy + y² when x = 6 and y = 5.
  30. 30.Use (a − b)² = a² − 2ab + b² to find 57².
  31. 31.Use (a + b)(a − b) = a² − b² to find 52 × 48.
  32. 32.If a + b = 20 and ab = 96, what is a² + b²?
  33. 33.Use (a + b)² = a² + 2ab + b² to find 77².
  34. 34.Use a² − b² = (a + b)(a − b) to find 47² − 12².
  35. 35.Use (a + b)² = a² + 2ab + b² to find 94².
  36. 36.Use (a + b)(a − b) = a² − b² to find 72 × 68.
  37. 37.Use (a − b)² = a² − 2ab + b² to find 13².
  38. 38.Find the value of x² + 2xy + y² when x = 12 and y = 7.
  39. 39.Use (a + b)² = a² + 2ab + b² to find 89².
  40. 40.Use (a + b)² = a² + 2ab + b² to find 16².

Answer key

  1. 5053
  2. 7744
  3. 2704
  4. 52
  5. 676
  6. 8649
  7. 6351
  8. 289
  9. 289
  10. 244
  11. 6355
  12. 1008
  13. 484
  14. 101
  15. 7056
  16. 169
  17. 1564
  18. 1024
  19. 1444
  20. 89
  21. 169
  22. 4489
  23. 4
  24. 7569
  25. 784
  26. 8165
  27. 361
  28. 97
  29. 121
  30. 3249
  31. 2496
  32. 208
  33. 5929
  34. 2065
  35. 8836
  36. 4896
  37. 169
  38. 361
  39. 7921
  40. 256

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