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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 636 · 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 65².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 33².
  3. 3.Use (a + b)² = a² + 2ab + b² to find 18².
  4. 4.Use a² − b² = (a + b)(a − b) to find 85² − 20².
  5. 5.Use (a + b)(a − b) = a² − b² to find 23 × 17.
  6. 6.If a − b = 3 and ab = 10, what is a² + b²?
  7. 7.Use a² − b² = (a + b)(a − b) to find 94² − 57².
  8. 8.If a + b = 11 and ab = 24, what is a² + b²?
  9. 9.Use (a + b)² = a² + 2ab + b² to find 44².
  10. 10.Use (a − b)² = a² − 2ab + b² to find 66².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 97².
  12. 12.If a + b = 5 and ab = 6, what is a² + b²?
  13. 13.Use (a − b)² = a² − 2ab + b² to find 49².
  14. 14.If a + b = 6 and ab = 5, what is a² + b²?
  15. 15.If a − b = 1 and ab = 2, what is a² + b²?
  16. 16.Use a² − b² = (a + b)(a − b) to find 31² − 1².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 47².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 73².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 76².
  20. 20.Find the value of x² + 2xy + y² when x = 11 and y = 2.
  21. 21.Find the value of x² − 2xy + y² when x = 8 and y = 3.
  22. 22.Use (a − b)² = a² − 2ab + b² to find 83².
  23. 23.Use a² − b² = (a + b)(a − b) to find 22² − 19².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 25².
  25. 25.Use (a + b)(a − b) = a² − b² to find 97 × 83.
  26. 26.Use (a − b)² = a² − 2ab + b² to find 21².
  27. 27.If a + b = 4 and ab = 3, what is a² + b²?
  28. 28.If a − b = 2 and ab = 24, what is a² + b²?
  29. 29.Use (a − b)² = a² − 2ab + b² to find 59².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 103².
  31. 31.Use (a + b)(a − b) = a² − b² to find 81 × 79.
  32. 32.Use (a − b)² = a² − 2ab + b² to find 68².
  33. 33.Find the value of x² − y² when x = 8 and y = 6.
  34. 34.Use (a − b)² = a² − 2ab + b² to find 31².
  35. 35.Use (a + b)(a − b) = a² − b² to find 46 × 34.
  36. 36.If a − b = 7 and ab = 44, what is a² + b²?
  37. 37.Find the value of x² + 2xy + y² when x = 13 and y = 2.
  38. 38.Find the value of x² − y² when x = 10 and y = 9.
  39. 39.If a + b = 7 and ab = 6, what is a² + b²?
  40. 40.Find the value of x² − 2xy + y² when x = 5 and y = 2.

Answer key

  1. 4225
  2. 1089
  3. 324
  4. 6825
  5. 391
  6. 29
  7. 5587
  8. 73
  9. 1936
  10. 4356
  11. 9409
  12. 13
  13. 2401
  14. 26
  15. 5
  16. 960
  17. 2209
  18. 5329
  19. 5776
  20. 169
  21. 25
  22. 6889
  23. 123
  24. 625
  25. 8051
  26. 441
  27. 10
  28. 52
  29. 3481
  30. 10609
  31. 6399
  32. 4624
  33. 28
  34. 961
  35. 1564
  36. 137
  37. 225
  38. 19
  39. 37
  40. 9

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