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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 330 · 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 91 × 89.
  2. 2.Use (a + b)(a − b) = a² − b² to find 78 × 62.
  3. 3.Find the value of x² − 2xy + y² when x = 8 and y = 5.
  4. 4.Use (a + b)² = a² + 2ab + b² to find 22².
  5. 5.Use (a − b)² = a² − 2ab + b² to find 92².
  6. 6.Use (a + b)(a − b) = a² − b² to find 94 × 86.
  7. 7.If a − b = 2 and ab = 48, what is a² + b²?
  8. 8.Use (a + b)(a − b) = a² − b² to find 79 × 61.
  9. 9.If a − b = 1 and ab = 72, what is a² + b²?
  10. 10.If a − b = 1 and ab = 30, what is a² + b²?
  11. 11.Use (a + b)(a − b) = a² − b² to find 68 × 52.
  12. 12.Use (a + b)² = a² + 2ab + b² to find 16².
  13. 13.Use (a + b)(a − b) = a² − b² to find 22 × 18.
  14. 14.Use (a − b)² = a² − 2ab + b² to find 25².
  15. 15.Find the value of x² − 2xy + y² when x = 4 and y = 3.
  16. 16.Use (a + b)² = a² + 2ab + b² to find 73².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 43².
  18. 18.Use (a + b)(a − b) = a² − b² to find 107 × 93.
  19. 19.Find the value of x² − 2xy + y² when x = 13 and y = 10.
  20. 20.If a + b = 7 and ab = 12, what is a² + b²?
  21. 21.If a + b = 7 and ab = 10, what is a² + b²?
  22. 22.Find the value of x² + 2xy + y² when x = 10 and y = 5.
  23. 23.Use (a − b)² = a² − 2ab + b² to find 72².
  24. 24.Use a² − b² = (a + b)(a − b) to find 20² − 8².
  25. 25.Use (a + b)(a − b) = a² − b² to find 73 × 67.
  26. 26.Use a² − b² = (a + b)(a − b) to find 22² − 5².
  27. 27.Use (a + b)(a − b) = a² − b² to find 36 × 24.
  28. 28.Use (a + b)² = a² + 2ab + b² to find 63².
  29. 29.Use (a − b)² = a² − 2ab + b² to find 99².
  30. 30.If a + b = 12 and ab = 35, what is a² + b²?
  31. 31.Find the value of x² − 2xy + y² when x = 3 and y = 1.
  32. 32.Use (a + b)(a − b) = a² − b² to find 83 × 77.
  33. 33.Find the value of x² − y² when x = 8 and y = 2.
  34. 34.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  35. 35.If a + b = 3 and ab = 2, what is a² + b²?
  36. 36.Use (a + b)² = a² + 2ab + b² to find 94².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 83².
  38. 38.If a + b = 23 and ab = 132, what is a² + b²?
  39. 39.Use (a + b)² = a² + 2ab + b² to find 108².
  40. 40.Use (a + b)² = a² + 2ab + b² to find 85².

Answer key

  1. 8099
  2. 4836
  3. 9
  4. 484
  5. 8464
  6. 8084
  7. 100
  8. 4819
  9. 145
  10. 61
  11. 3536
  12. 256
  13. 396
  14. 625
  15. 1
  16. 5329
  17. 1849
  18. 9951
  19. 9
  20. 25
  21. 29
  22. 225
  23. 5184
  24. 336
  25. 4891
  26. 459
  27. 864
  28. 3969
  29. 9801
  30. 74
  31. 4
  32. 6391
  33. 60
  34. 875
  35. 5
  36. 8836
  37. 6889
  38. 265
  39. 11664
  40. 7225

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