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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 802 · 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)(a − b) = a² − b² to find 75 × 65.
  2. 2.Use a² − b² = (a + b)(a − b) to find 33² − 9².
  3. 3.Use a² − b² = (a + b)(a − b) to find 40² − 27².
  4. 4.Use (a − b)² = a² − 2ab + b² to find 47².
  5. 5.Use (a − b)² = a² − 2ab + b² to find 13².
  6. 6.Use (a + b)² = a² + 2ab + b² to find 41².
  7. 7.If a − b = 4 and ab = 5, what is a² + b²?
  8. 8.Use (a − b)² = a² − 2ab + b² to find 86².
  9. 9.Use (a − b)² = a² − 2ab + b² to find 17².
  10. 10.Use a² − b² = (a + b)(a − b) to find 65² − 30².
  11. 11.Use (a + b)² = a² + 2ab + b² to find 59².
  12. 12.Use a² − b² = (a + b)(a − b) to find 90² − 61².
  13. 13.Use (a + b)² = a² + 2ab + b² to find 11².
  14. 14.Use (a + b)² = a² + 2ab + b² to find 27².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 23².
  16. 16.Use a² − b² = (a + b)(a − b) to find 25² − 12².
  17. 17.Use a² − b² = (a + b)(a − b) to find 52² − 46².
  18. 18.Use (a + b)² = a² + 2ab + b² to find 78².
  19. 19.Use (a + b)(a − b) = a² − b² to find 95 × 85.
  20. 20.Use (a + b)(a − b) = a² − b² to find 54 × 46.
  21. 21.Use (a + b)(a − b) = a² − b² to find 102 × 98.
  22. 22.Use a² − b² = (a + b)(a − b) to find 28² − 2².
  23. 23.Use a² − b² = (a + b)(a − b) to find 37² − 16².
  24. 24.Find the value of x² + 2xy + y² when x = 11 and y = 4.
  25. 25.Use (a + b)(a − b) = a² − b² to find 68 × 52.
  26. 26.Use a² − b² = (a + b)(a − b) to find 65² − 33².
  27. 27.Use a² − b² = (a + b)(a − b) to find 70² − 36².
  28. 28.Find the value of x² − 2xy + y² when x = 9 and y = 1.
  29. 29.If a − b = 1 and ab = 20, what is a² + b²?
  30. 30.Find the value of x² − 2xy + y² when x = 3 and y = 1.
  31. 31.Use a² − b² = (a + b)(a − b) to find 40² − 11².
  32. 32.Use (a + b)² = a² + 2ab + b² to find 63².
  33. 33.Use (a + b)(a − b) = a² − b² to find 103 × 97.
  34. 34.Use (a + b)(a − b) = a² − b² to find 106 × 94.
  35. 35.Use a² − b² = (a + b)(a − b) to find 34² − 10².
  36. 36.If a − b = 1 and ab = 56, what is a² + b²?
  37. 37.If a + b = 16 and ab = 55, what is a² + b²?
  38. 38.Use (a − b)² = a² − 2ab + b² to find 61².
  39. 39.Use a² − b² = (a + b)(a − b) to find 32² − 10².
  40. 40.Use (a + b)(a − b) = a² − b² to find 34 × 26.

Answer key

  1. 4875
  2. 1008
  3. 871
  4. 2209
  5. 169
  6. 1681
  7. 26
  8. 7396
  9. 289
  10. 3325
  11. 3481
  12. 4379
  13. 121
  14. 729
  15. 529
  16. 481
  17. 588
  18. 6084
  19. 8075
  20. 2484
  21. 9996
  22. 780
  23. 1113
  24. 225
  25. 3536
  26. 3136
  27. 3604
  28. 64
  29. 41
  30. 4
  31. 1479
  32. 3969
  33. 9991
  34. 9964
  35. 1056
  36. 113
  37. 146
  38. 3721
  39. 924
  40. 884

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