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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 573 · 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 38 × 22.
  2. 2.Use (a + b)² = a² + 2ab + b² to find 25².
  3. 3.Use (a + b)(a − b) = a² − b² to find 105 × 95.
  4. 4.Use a² − b² = (a + b)(a − b) to find 64² − 3².
  5. 5.Find the value of x² + 2xy + y² when x = 14 and y = 7.
  6. 6.Use (a + b)(a − b) = a² − b² to find 107 × 93.
  7. 7.Find the value of x² + 2xy + y² when x = 3 and y = 1.
  8. 8.Use (a + b)² = a² + 2ab + b² to find 14².
  9. 9.Use a² − b² = (a + b)(a − b) to find 44² − 2².
  10. 10.Use a² − b² = (a + b)(a − b) to find 30² − 5².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 75².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 22².
  13. 13.Use (a + b)² = a² + 2ab + b² to find 103².
  14. 14.Use (a + b)(a − b) = a² − b² to find 103 × 97.
  15. 15.Use (a + b)(a − b) = a² − b² to find 76 × 64.
  16. 16.Use (a + b)² = a² + 2ab + b² to find 44².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 24².
  18. 18.If a + b = 10 and ab = 21, what is a² + b²?
  19. 19.Use (a − b)² = a² − 2ab + b² to find 56².
  20. 20.Use (a + b)² = a² + 2ab + b² to find 36².
  21. 21.Use a² − b² = (a + b)(a − b) to find 66² − 56².
  22. 22.If a + b = 11 and ab = 30, what is a² + b²?
  23. 23.If a + b = 5 and ab = 6, what is a² + b²?
  24. 24.Use (a − b)² = a² − 2ab + b² to find 62².
  25. 25.Use (a + b)² = a² + 2ab + b² to find 26².
  26. 26.Use (a + b)(a − b) = a² − b² to find 66 × 54.
  27. 27.Use a² − b² = (a + b)(a − b) to find 24² − 14².
  28. 28.Find the value of x² − 2xy + y² when x = 5 and y = 4.
  29. 29.Use (a − b)² = a² − 2ab + b² to find 67².
  30. 30.If a − b = 1 and ab = 30, what is a² + b²?
  31. 31.Use (a − b)² = a² − 2ab + b² to find 42².
  32. 32.Find the value of x² − y² when x = 3 and y = 1.
  33. 33.Use (a + b)² = a² + 2ab + b² to find 89².
  34. 34.If a + b = 4 and ab = 3, what is a² + b²?
  35. 35.Use (a + b)(a − b) = a² − b² to find 84 × 76.
  36. 36.Use (a + b)² = a² + 2ab + b² to find 17².
  37. 37.Use a² − b² = (a + b)(a − b) to find 60² − 39².
  38. 38.If a − b = 1 and ab = 2, what is a² + b²?
  39. 39.Use a² − b² = (a + b)(a − b) to find 90² − 51².
  40. 40.If a − b = 2 and ab = 3, what is a² + b²?

Answer key

  1. 836
  2. 625
  3. 9975
  4. 4087
  5. 441
  6. 9951
  7. 16
  8. 196
  9. 1932
  10. 875
  11. 5625
  12. 484
  13. 10609
  14. 9991
  15. 4864
  16. 1936
  17. 576
  18. 58
  19. 3136
  20. 1296
  21. 1220
  22. 61
  23. 13
  24. 3844
  25. 676
  26. 3564
  27. 380
  28. 1
  29. 4489
  30. 61
  31. 1764
  32. 8
  33. 7921
  34. 10
  35. 6384
  36. 289
  37. 2079
  38. 5
  39. 5499
  40. 10

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