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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 196 · 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 66 × 54.
  2. 2.Use (a + b)(a − b) = a² − b² to find 73 × 67.
  3. 3.Find the value of x² − y² when x = 11 and y = 8.
  4. 4.Use a² − b² = (a + b)(a − b) to find 54² − 15².
  5. 5.Find the value of x² − y² when x = 11 and y = 1.
  6. 6.If a − b = 3 and ab = 108, what is a² + b²?
  7. 7.Find the value of x² − y² when x = 13 and y = 2.
  8. 8.Use (a + b)(a − b) = a² − b² to find 56 × 44.
  9. 9.Use a² − b² = (a + b)(a − b) to find 91² − 35².
  10. 10.Use (a − b)² = a² − 2ab + b² to find 56².
  11. 11.Find the value of x² − 2xy + y² when x = 15 and y = 13.
  12. 12.Find the value of x² − y² when x = 13 and y = 10.
  13. 13.Use (a + b)(a − b) = a² − b² to find 71 × 69.
  14. 14.Find the value of x² − 2xy + y² when x = 12 and y = 5.
  15. 15.Use (a + b)(a − b) = a² − b² to find 25 × 15.
  16. 16.Use (a − b)² = a² − 2ab + b² to find 71².
  17. 17.Use (a + b)(a − b) = a² − b² to find 83 × 77.
  18. 18.Find the value of x² − 2xy + y² when x = 3 and y = 2.
  19. 19.Use a² − b² = (a + b)(a − b) to find 40² − 23².
  20. 20.Use (a + b)² = a² + 2ab + b² to find 13².
  21. 21.Find the value of x² − 2xy + y² when x = 5 and y = 4.
  22. 22.Use a² − b² = (a + b)(a − b) to find 24² − 5².
  23. 23.Use (a + b)² = a² + 2ab + b² to find 49².
  24. 24.Use (a − b)² = a² − 2ab + b² to find 46².
  25. 25.If a + b = 4 and ab = 3, what is a² + b²?
  26. 26.Use (a + b)² = a² + 2ab + b² to find 19².
  27. 27.Use a² − b² = (a + b)(a − b) to find 93² − 59².
  28. 28.Find the value of x² − y² when x = 12 and y = 7.
  29. 29.Use (a + b)² = a² + 2ab + b² to find 25².
  30. 30.Use (a − b)² = a² − 2ab + b² to find 23².
  31. 31.If a − b = 1 and ab = 20, what is a² + b²?
  32. 32.Use a² − b² = (a + b)(a − b) to find 44² − 6².
  33. 33.Use a² − b² = (a + b)(a − b) to find 25² − 7².
  34. 34.Use a² − b² = (a + b)(a − b) to find 76² − 70².
  35. 35.Use a² − b² = (a + b)(a − b) to find 28² − 24².
  36. 36.Use a² − b² = (a + b)(a − b) to find 71² − 62².
  37. 37.Find the value of x² − y² when x = 9 and y = 2.
  38. 38.Use (a − b)² = a² − 2ab + b² to find 64².
  39. 39.Use (a + b)(a − b) = a² − b² to find 102 × 98.
  40. 40.Use (a + b)² = a² + 2ab + b² to find 41².

Answer key

  1. 3564
  2. 4891
  3. 57
  4. 2691
  5. 120
  6. 225
  7. 165
  8. 2464
  9. 7056
  10. 3136
  11. 4
  12. 69
  13. 4899
  14. 49
  15. 375
  16. 5041
  17. 6391
  18. 1
  19. 1071
  20. 169
  21. 1
  22. 551
  23. 2401
  24. 2116
  25. 10
  26. 361
  27. 5168
  28. 95
  29. 625
  30. 529
  31. 41
  32. 1900
  33. 576
  34. 876
  35. 208
  36. 1197
  37. 77
  38. 4096
  39. 9996
  40. 1681

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