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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 671 · 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.Find the value of x² − 2xy + y² when x = 5 and y = 3.
  2. 2.Use a² − b² = (a + b)(a − b) to find 21² − 6².
  3. 3.If a + b = 11 and ab = 24, what is a² + b²?
  4. 4.Use (a + b)² = a² + 2ab + b² to find 83².
  5. 5.Find the value of x² + 2xy + y² when x = 6 and y = 3.
  6. 6.Use (a + b)(a − b) = a² − b² to find 33 × 27.
  7. 7.If a + b = 9 and ab = 18, what is a² + b²?
  8. 8.Use a² − b² = (a + b)(a − b) to find 30² − 4².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 77².
  10. 10.Use (a + b)² = a² + 2ab + b² to find 13².
  11. 11.Use (a + b)² = a² + 2ab + b² to find 82².
  12. 12.Find the value of x² − 2xy + y² when x = 13 and y = 1.
  13. 13.Use (a + b)(a − b) = a² − b² to find 29 × 11.
  14. 14.Use (a + b)(a − b) = a² − b² to find 21 × 19.
  15. 15.Use a² − b² = (a + b)(a − b) to find 75² − 25².
  16. 16.Find the value of x² − y² when x = 13 and y = 7.
  17. 17.Use a² − b² = (a + b)(a − b) to find 86² − 57².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 31².
  19. 19.If a + b = 5 and ab = 6, what is a² + b²?
  20. 20.Use (a + b)(a − b) = a² − b² to find 27 × 13.
  21. 21.Use (a + b)² = a² + 2ab + b² to find 76².
  22. 22.If a − b = 7 and ab = 30, what is a² + b²?
  23. 23.Find the value of x² + 2xy + y² when x = 8 and y = 6.
  24. 24.Use (a + b)² = a² + 2ab + b² to find 47².
  25. 25.Use a² − b² = (a + b)(a − b) to find 23² − 19².
  26. 26.Use a² − b² = (a + b)(a − b) to find 77² − 27².
  27. 27.Use a² − b² = (a + b)(a − b) to find 50² − 44².
  28. 28.Find the value of x² − y² when x = 13 and y = 6.
  29. 29.Use (a + b)² = a² + 2ab + b² to find 65².
  30. 30.Find the value of x² − y² when x = 6 and y = 3.
  31. 31.Use (a − b)² = a² − 2ab + b² to find 28².
  32. 32.Use (a − b)² = a² − 2ab + b² to find 94².
  33. 33.Use a² − b² = (a + b)(a − b) to find 97² − 41².
  34. 34.Use a² − b² = (a + b)(a − b) to find 63² − 58².
  35. 35.Use (a − b)² = a² − 2ab + b² to find 36².
  36. 36.Use a² − b² = (a + b)(a − b) to find 91² − 14².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 19².
  38. 38.Use a² − b² = (a + b)(a − b) to find 34² − 27².
  39. 39.Use (a + b)(a − b) = a² − b² to find 59 × 41.
  40. 40.Use (a + b)(a − b) = a² − b² to find 31 × 29.

Answer key

  1. 4
  2. 405
  3. 73
  4. 6889
  5. 81
  6. 891
  7. 45
  8. 884
  9. 5929
  10. 169
  11. 6724
  12. 144
  13. 319
  14. 399
  15. 5000
  16. 120
  17. 4147
  18. 961
  19. 13
  20. 351
  21. 5776
  22. 109
  23. 196
  24. 2209
  25. 168
  26. 5200
  27. 564
  28. 133
  29. 4225
  30. 27
  31. 784
  32. 8836
  33. 7728
  34. 605
  35. 1296
  36. 8085
  37. 361
  38. 427
  39. 2419
  40. 899

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