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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 960 · 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 66².
  2. 2.Use (a − b)² = a² − 2ab + b² to find 59².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 83².
  4. 4.Use a² − b² = (a + b)(a − b) to find 80² − 53².
  5. 5.If a − b = 1 and ab = 72, what is a² + b²?
  6. 6.If a + b = 16 and ab = 48, what is a² + b²?
  7. 7.Use (a − b)² = a² − 2ab + b² to find 99².
  8. 8.Use (a + b)² = a² + 2ab + b² to find 69².
  9. 9.Use a² − b² = (a + b)(a − b) to find 59² − 3².
  10. 10.If a + b = 12 and ab = 11, what is a² + b²?
  11. 11.Use a² − b² = (a + b)(a − b) to find 21² − 6².
  12. 12.Use (a + b)² = a² + 2ab + b² to find 87².
  13. 13.Use (a + b)² = a² + 2ab + b² to find 42².
  14. 14.Use (a + b)² = a² + 2ab + b² to find 71².
  15. 15.Use (a + b)² = a² + 2ab + b² to find 66².
  16. 16.If a − b = 5 and ab = 66, what is a² + b²?
  17. 17.Use a² − b² = (a + b)(a − b) to find 43² − 12².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 73².
  19. 19.Find the value of x² − 2xy + y² when x = 4 and y = 2.
  20. 20.Use a² − b² = (a + b)(a − b) to find 33² − 4².
  21. 21.Use a² − b² = (a + b)(a − b) to find 27² − 11².
  22. 22.Use (a + b)(a − b) = a² − b² to find 41 × 39.
  23. 23.If a + b = 9 and ab = 8, what is a² + b²?
  24. 24.Use (a − b)² = a² − 2ab + b² to find 16².
  25. 25.Use a² − b² = (a + b)(a − b) to find 60² − 48².
  26. 26.Use (a − b)² = a² − 2ab + b² to find 61².
  27. 27.Use (a − b)² = a² − 2ab + b² to find 75².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 51².
  29. 29.If a + b = 22 and ab = 120, what is a² + b²?
  30. 30.Use (a − b)² = a² − 2ab + b² to find 53².
  31. 31.Use (a + b)² = a² + 2ab + b² to find 82².
  32. 32.Use (a − b)² = a² − 2ab + b² to find 91².
  33. 33.Use a² − b² = (a + b)(a − b) to find 59² − 38².
  34. 34.Find the value of x² − y² when x = 8 and y = 2.
  35. 35.Use (a + b)² = a² + 2ab + b² to find 37².
  36. 36.Use (a − b)² = a² − 2ab + b² to find 26².
  37. 37.Find the value of x² + 2xy + y² when x = 4 and y = 3.
  38. 38.Use a² − b² = (a + b)(a − b) to find 28² − 19².
  39. 39.If a − b = 2 and ab = 63, what is a² + b²?
  40. 40.Use (a + b)(a − b) = a² − b² to find 66 × 54.

Answer key

  1. 4356
  2. 3481
  3. 6889
  4. 3591
  5. 145
  6. 160
  7. 9801
  8. 4761
  9. 3472
  10. 122
  11. 405
  12. 7569
  13. 1764
  14. 5041
  15. 4356
  16. 157
  17. 1705
  18. 5329
  19. 4
  20. 1073
  21. 608
  22. 1599
  23. 65
  24. 256
  25. 1296
  26. 3721
  27. 5625
  28. 2601
  29. 244
  30. 2809
  31. 6724
  32. 8281
  33. 2037
  34. 60
  35. 1369
  36. 676
  37. 49
  38. 423
  39. 130
  40. 3564

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