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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 882 · 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 27².
  2. 2.Use (a − b)² = a² − 2ab + b² to find 64².
  3. 3.Use (a + b)² = a² + 2ab + b² to find 32².
  4. 4.If a − b = 3 and ab = 10, what is a² + b²?
  5. 5.Use (a − b)² = a² − 2ab + b² to find 69².
  6. 6.If a + b = 3 and ab = 2, what is a² + b²?
  7. 7.Use (a − b)² = a² − 2ab + b² to find 65².
  8. 8.Use (a + b)² = a² + 2ab + b² to find 55².
  9. 9.Find the value of x² − y² when x = 5 and y = 2.
  10. 10.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  11. 11.Use (a + b)(a − b) = a² − b² to find 54 × 46.
  12. 12.If a + b = 9 and ab = 14, what is a² + b²?
  13. 13.Use (a − b)² = a² − 2ab + b² to find 17².
  14. 14.Find the value of x² − 2xy + y² when x = 14 and y = 4.
  15. 15.Use a² − b² = (a + b)(a − b) to find 51² − 18².
  16. 16.If a + b = 17 and ab = 60, what is a² + b²?
  17. 17.Use a² − b² = (a + b)(a − b) to find 49² − 12².
  18. 18.Use (a + b)² = a² + 2ab + b² to find 33².
  19. 19.Use (a − b)² = a² − 2ab + b² to find 29².
  20. 20.Use a² − b² = (a + b)(a − b) to find 21² − 2².
  21. 21.Use (a − b)² = a² − 2ab + b² to find 32².
  22. 22.Use (a − b)² = a² − 2ab + b² to find 21².
  23. 23.Use (a + b)² = a² + 2ab + b² to find 15².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 11².
  25. 25.Use (a − b)² = a² − 2ab + b² to find 74².
  26. 26.Use a² − b² = (a + b)(a − b) to find 49² − 28².
  27. 27.Use (a + b)(a − b) = a² − b² to find 73 × 67.
  28. 28.If a − b = 2 and ab = 15, what is a² + b²?
  29. 29.Use a² − b² = (a + b)(a − b) to find 30² − 6².
  30. 30.Use a² − b² = (a + b)(a − b) to find 53² − 45².
  31. 31.Use (a + b)² = a² + 2ab + b² to find 44².
  32. 32.If a + b = 16 and ab = 63, what is a² + b²?
  33. 33.Find the value of x² − 2xy + y² when x = 8 and y = 6.
  34. 34.Use (a − b)² = a² − 2ab + b² to find 81².
  35. 35.Use (a + b)² = a² + 2ab + b² to find 109².
  36. 36.Use a² − b² = (a + b)(a − b) to find 77² − 70².
  37. 37.Use a² − b² = (a + b)(a − b) to find 51² − 20².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 52².
  39. 39.Use (a − b)² = a² − 2ab + b² to find 42².
  40. 40.Use (a + b)(a − b) = a² − b² to find 43 × 37.

Answer key

  1. 729
  2. 4096
  3. 1024
  4. 29
  5. 4761
  6. 5
  7. 4225
  8. 3025
  9. 21
  10. 899
  11. 2484
  12. 53
  13. 289
  14. 100
  15. 2277
  16. 169
  17. 2257
  18. 1089
  19. 841
  20. 437
  21. 1024
  22. 441
  23. 225
  24. 121
  25. 5476
  26. 1617
  27. 4891
  28. 34
  29. 864
  30. 784
  31. 1936
  32. 130
  33. 4
  34. 6561
  35. 11881
  36. 1029
  37. 2201
  38. 2704
  39. 1764
  40. 1591

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