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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 296 · 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 35².
  2. 2.Use (a + b)(a − b) = a² − b² to find 96 × 84.
  3. 3.Use (a − b)² = a² − 2ab + b² to find 87².
  4. 4.Use (a + b)² = a² + 2ab + b² to find 74².
  5. 5.Use a² − b² = (a + b)(a − b) to find 20² − 16².
  6. 6.Use (a + b)² = a² + 2ab + b² to find 108².
  7. 7.Use (a + b)(a − b) = a² − b² to find 108 × 92.
  8. 8.Use (a + b)(a − b) = a² − b² to find 103 × 97.
  9. 9.Use (a + b)(a − b) = a² − b² to find 51 × 49.
  10. 10.Use (a + b)² = a² + 2ab + b² to find 18².
  11. 11.If a + b = 12 and ab = 32, what is a² + b²?
  12. 12.Find the value of x² + 2xy + y² when x = 4 and y = 2.
  13. 13.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  14. 14.Use a² − b² = (a + b)(a − b) to find 90² − 36².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 81².
  16. 16.Use (a + b)(a − b) = a² − b² to find 63 × 57.
  17. 17.Use (a − b)² = a² − 2ab + b² to find 26².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 18².
  19. 19.Use a² − b² = (a + b)(a − b) to find 82² − 66².
  20. 20.If a + b = 14 and ab = 40, what is a² + b²?
  21. 21.Use (a + b)² = a² + 2ab + b² to find 59².
  22. 22.Use (a + b)² = a² + 2ab + b² to find 79².
  23. 23.If a − b = 4 and ab = 21, what is a² + b²?
  24. 24.Use (a − b)² = a² − 2ab + b² to find 66².
  25. 25.Use (a + b)² = a² + 2ab + b² to find 32².
  26. 26.Use a² − b² = (a + b)(a − b) to find 41² − 38².
  27. 27.Use (a + b)² = a² + 2ab + b² to find 37².
  28. 28.Use (a − b)² = a² − 2ab + b² to find 61².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 29².
  30. 30.If a − b = 1 and ab = 2, what is a² + b²?
  31. 31.Use (a − b)² = a² − 2ab + b² to find 74².
  32. 32.Use (a − b)² = a² − 2ab + b² to find 42².
  33. 33.Use a² − b² = (a + b)(a − b) to find 52² − 49².
  34. 34.Use (a + b)(a − b) = a² − b² to find 73 × 67.
  35. 35.Use a² − b² = (a + b)(a − b) to find 74² − 46².
  36. 36.Use (a + b)(a − b) = a² − b² to find 107 × 93.
  37. 37.Use (a − b)² = a² − 2ab + b² to find 85².
  38. 38.Use (a + b)² = a² + 2ab + b² to find 85².
  39. 39.Find the value of x² − y² when x = 9 and y = 4.
  40. 40.If a − b = 3 and ab = 10, what is a² + b²?

Answer key

  1. 1225
  2. 8064
  3. 7569
  4. 5476
  5. 144
  6. 11664
  7. 9936
  8. 9991
  9. 2499
  10. 324
  11. 80
  12. 36
  13. 25
  14. 6804
  15. 6561
  16. 3591
  17. 676
  18. 324
  19. 2368
  20. 116
  21. 3481
  22. 6241
  23. 58
  24. 4356
  25. 1024
  26. 237
  27. 1369
  28. 3721
  29. 841
  30. 5
  31. 5476
  32. 1764
  33. 303
  34. 4891
  35. 3360
  36. 9951
  37. 7225
  38. 7225
  39. 65
  40. 29

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