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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 249 · 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 64².
  2. 2.Use (a − b)² = a² − 2ab + b² to find 17².
  3. 3.Use (a + b)(a − b) = a² − b² to find 45 × 35.
  4. 4.Use (a + b)² = a² + 2ab + b² to find 12².
  5. 5.Use (a − b)² = a² − 2ab + b² to find 34².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 73².
  7. 7.Use a² − b² = (a + b)(a − b) to find 24² − 3².
  8. 8.If a − b = 4 and ab = 77, what is a² + b²?
  9. 9.Use (a + b)(a − b) = a² − b² to find 102 × 98.
  10. 10.If a + b = 16 and ab = 55, what is a² + b²?
  11. 11.If a + b = 4 and ab = 3, what is a² + b²?
  12. 12.Use a² − b² = (a + b)(a − b) to find 20² − 2².
  13. 13.Use (a + b)² = a² + 2ab + b² to find 88².
  14. 14.Find the value of x² − 2xy + y² when x = 10 and y = 6.
  15. 15.Use (a + b)(a − b) = a² − b² to find 83 × 77.
  16. 16.Find the value of x² − y² when x = 15 and y = 12.
  17. 17.Use a² − b² = (a + b)(a − b) to find 21² − 12².
  18. 18.Use a² − b² = (a + b)(a − b) to find 59² − 25².
  19. 19.Use (a − b)² = a² − 2ab + b² to find 94².
  20. 20.Find the value of x² − y² when x = 5 and y = 1.
  21. 21.Use a² − b² = (a + b)(a − b) to find 99² − 91².
  22. 22.Find the value of x² + 2xy + y² when x = 10 and y = 8.
  23. 23.If a − b = 2 and ab = 48, what is a² + b²?
  24. 24.Use (a + b)(a − b) = a² − b² to find 38 × 22.
  25. 25.Use (a + b)² = a² + 2ab + b² to find 39².
  26. 26.Use a² − b² = (a + b)(a − b) to find 75² − 37².
  27. 27.Use (a − b)² = a² − 2ab + b² to find 22².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 72².
  29. 29.If a + b = 13 and ab = 30, what is a² + b²?
  30. 30.Use a² − b² = (a + b)(a − b) to find 94² − 71².
  31. 31.Use (a − b)² = a² − 2ab + b² to find 33².
  32. 32.Use (a + b)(a − b) = a² − b² to find 42 × 38.
  33. 33.If a − b = 2 and ab = 99, what is a² + b²?
  34. 34.Use (a + b)² = a² + 2ab + b² to find 77².
  35. 35.Use a² − b² = (a + b)(a − b) to find 46² − 20².
  36. 36.Use (a − b)² = a² − 2ab + b² to find 45².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 86².
  38. 38.Find the value of x² − 2xy + y² when x = 8 and y = 2.
  39. 39.If a + b = 3 and ab = 2, what is a² + b²?
  40. 40.Find the value of x² − 2xy + y² when x = 15 and y = 13.

Answer key

  1. 4096
  2. 289
  3. 1575
  4. 144
  5. 1156
  6. 5329
  7. 567
  8. 170
  9. 9996
  10. 146
  11. 10
  12. 396
  13. 7744
  14. 16
  15. 6391
  16. 81
  17. 297
  18. 2856
  19. 8836
  20. 24
  21. 1520
  22. 324
  23. 100
  24. 836
  25. 1521
  26. 4256
  27. 484
  28. 5184
  29. 109
  30. 3795
  31. 1089
  32. 1596
  33. 202
  34. 5929
  35. 1716
  36. 2025
  37. 7396
  38. 36
  39. 5
  40. 4

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