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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 501 · 40 sums
TalentJR

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 36².
  3. 3.Use (a + b)(a − b) = a² − b² to find 103 × 97.
  4. 4.Use (a − b)² = a² − 2ab + b² to find 23².
  5. 5.Find the value of x² − 2xy + y² when x = 5 and y = 3.
  6. 6.If a − b = 1 and ab = 6, what is a² + b²?
  7. 7.Use (a + b)(a − b) = a² − b² to find 42 × 38.
  8. 8.Use (a + b)(a − b) = a² − b² to find 104 × 96.
  9. 9.Use (a + b)² = a² + 2ab + b² to find 43².
  10. 10.Use a² − b² = (a + b)(a − b) to find 56² − 26².
  11. 11.Use (a + b)(a − b) = a² − b² to find 81 × 79.
  12. 12.Use (a + b)(a − b) = a² − b² to find 72 × 68.
  13. 13.Use (a + b)² = a² + 2ab + b² to find 56².
  14. 14.Use (a − b)² = a² − 2ab + b² to find 42².
  15. 15.Use (a + b)² = a² + 2ab + b² to find 85².
  16. 16.Use a² − b² = (a + b)(a − b) to find 95² − 30².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 26².
  18. 18.Use (a + b)(a − b) = a² − b² to find 46 × 34.
  19. 19.Use (a + b)(a − b) = a² − b² to find 95 × 85.
  20. 20.Use (a − b)² = a² − 2ab + b² to find 71².
  21. 21.Use a² − b² = (a + b)(a − b) to find 29² − 2².
  22. 22.Use a² − b² = (a + b)(a − b) to find 22² − 3².
  23. 23.Use a² − b² = (a + b)(a − b) to find 63² − 13².
  24. 24.If a + b = 4 and ab = 3, what is a² + b²?
  25. 25.Use (a − b)² = a² − 2ab + b² to find 69².
  26. 26.Use (a + b)² = a² + 2ab + b² to find 18².
  27. 27.Use a² − b² = (a + b)(a − b) to find 97² − 60².
  28. 28.Use a² − b² = (a + b)(a − b) to find 80² − 73².
  29. 29.Use a² − b² = (a + b)(a − b) to find 69² − 19².
  30. 30.Use (a − b)² = a² − 2ab + b² to find 41².
  31. 31.Use (a − b)² = a² − 2ab + b² to find 83².
  32. 32.Use (a + b)(a − b) = a² − b² to find 85 × 75.
  33. 33.Use (a + b)(a − b) = a² − b² to find 45 × 35.
  34. 34.If a − b = 4 and ab = 5, what is a² + b²?
  35. 35.Use (a + b)² = a² + 2ab + b² to find 52².
  36. 36.Find the value of x² − y² when x = 5 and y = 2.
  37. 37.Use (a − b)² = a² − 2ab + b² to find 44².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 87².
  39. 39.Use a² − b² = (a + b)(a − b) to find 31² − 12².
  40. 40.Use (a + b)² = a² + 2ab + b² to find 55².

Answer key

  1. 4096
  2. 1296
  3. 9991
  4. 529
  5. 4
  6. 13
  7. 1596
  8. 9984
  9. 1849
  10. 2460
  11. 6399
  12. 4896
  13. 3136
  14. 1764
  15. 7225
  16. 8125
  17. 676
  18. 1564
  19. 8075
  20. 5041
  21. 837
  22. 475
  23. 3800
  24. 10
  25. 4761
  26. 324
  27. 5809
  28. 1071
  29. 4400
  30. 1681
  31. 6889
  32. 6375
  33. 1575
  34. 26
  35. 2704
  36. 21
  37. 1936
  38. 7569
  39. 817
  40. 3025

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