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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 503 · 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 61².
  2. 2.Use (a + b)(a − b) = a² − b² to find 36 × 24.
  3. 3.Use (a + b)² = a² + 2ab + b² to find 86².
  4. 4.Use (a + b)² = a² + 2ab + b² to find 102².
  5. 5.Use (a + b)² = a² + 2ab + b² to find 92².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 39².
  7. 7.Find the value of x² + 2xy + y² when x = 11 and y = 9.
  8. 8.Use a² − b² = (a + b)(a − b) to find 96² − 55².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 54².
  10. 10.If a + b = 15 and ab = 36, what is a² + b²?
  11. 11.Use (a + b)(a − b) = a² − b² to find 44 × 36.
  12. 12.Find the value of x² + 2xy + y² when x = 11 and y = 1.
  13. 13.Find the value of x² + 2xy + y² when x = 9 and y = 6.
  14. 14.Use (a + b)(a − b) = a² − b² to find 109 × 91.
  15. 15.Use a² − b² = (a + b)(a − b) to find 20² − 17².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 12².
  17. 17.Use (a + b)(a − b) = a² − b² to find 34 × 26.
  18. 18.Use (a + b)² = a² + 2ab + b² to find 22².
  19. 19.If a + b = 21 and ab = 108, what is a² + b²?
  20. 20.Find the value of x² + 2xy + y² when x = 3 and y = 1.
  21. 21.Use (a + b)(a − b) = a² − b² to find 65 × 55.
  22. 22.Use (a − b)² = a² − 2ab + b² to find 77².
  23. 23.Use (a − b)² = a² − 2ab + b² to find 14².
  24. 24.Find the value of x² − y² when x = 9 and y = 1.
  25. 25.If a − b = 6 and ab = 7, what is a² + b²?
  26. 26.If a − b = 3 and ab = 108, what is a² + b²?
  27. 27.Use (a + b)² = a² + 2ab + b² to find 82².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 103².
  29. 29.Use (a − b)² = a² − 2ab + b² to find 88².
  30. 30.Use (a − b)² = a² − 2ab + b² to find 45².
  31. 31.Use (a + b)² = a² + 2ab + b² to find 85².
  32. 32.Use a² − b² = (a + b)(a − b) to find 29² − 5².
  33. 33.Use (a + b)(a − b) = a² − b² to find 77 × 63.
  34. 34.Find the value of x² + 2xy + y² when x = 14 and y = 3.
  35. 35.Use a² − b² = (a + b)(a − b) to find 95² − 39².
  36. 36.Use a² − b² = (a + b)(a − b) to find 25² − 15².
  37. 37.Find the value of x² − y² when x = 5 and y = 1.
  38. 38.If a − b = 1 and ab = 2, what is a² + b²?
  39. 39.Use a² − b² = (a + b)(a − b) to find 32² − 26².
  40. 40.Use (a + b)² = a² + 2ab + b² to find 78².

Answer key

  1. 3721
  2. 864
  3. 7396
  4. 10404
  5. 8464
  6. 1521
  7. 400
  8. 6191
  9. 2916
  10. 153
  11. 1584
  12. 144
  13. 225
  14. 9919
  15. 111
  16. 144
  17. 884
  18. 484
  19. 225
  20. 16
  21. 3575
  22. 5929
  23. 196
  24. 80
  25. 50
  26. 225
  27. 6724
  28. 10609
  29. 7744
  30. 2025
  31. 7225
  32. 816
  33. 4851
  34. 289
  35. 7504
  36. 400
  37. 24
  38. 5
  39. 348
  40. 6084

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