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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 988 · 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.If a − b = 1 and ab = 6, what is a² + b²?
  2. 2.Use (a + b)² = a² + 2ab + b² to find 11².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 51².
  4. 4.Use (a + b)(a − b) = a² − b² to find 98 × 82.
  5. 5.Use (a + b)² = a² + 2ab + b² to find 98².
  6. 6.Use a² − b² = (a + b)(a − b) to find 68² − 57².
  7. 7.If a − b = 1 and ab = 20, what is a² + b²?
  8. 8.Use (a + b)(a − b) = a² − b² to find 88 × 72.
  9. 9.Use (a + b)(a − b) = a² − b² to find 68 × 52.
  10. 10.Use (a + b)² = a² + 2ab + b² to find 81².
  11. 11.Use a² − b² = (a + b)(a − b) to find 32² − 24².
  12. 12.Find the value of x² + 2xy + y² when x = 8 and y = 4.
  13. 13.Use a² − b² = (a + b)(a − b) to find 65² − 52².
  14. 14.If a + b = 3 and ab = 2, what is a² + b²?
  15. 15.Use (a + b)² = a² + 2ab + b² to find 67².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 101².
  17. 17.Use (a + b)(a − b) = a² − b² to find 67 × 53.
  18. 18.Use a² − b² = (a + b)(a − b) to find 37² − 29².
  19. 19.If a − b = 4 and ab = 5, what is a² + b²?
  20. 20.Find the value of x² − 2xy + y² when x = 4 and y = 2.
  21. 21.Use (a + b)(a − b) = a² − b² to find 94 × 86.
  22. 22.Find the value of x² − 2xy + y² when x = 7 and y = 6.
  23. 23.If a − b = 4 and ab = 60, what is a² + b²?
  24. 24.If a + b = 11 and ab = 28, what is a² + b²?
  25. 25.Use (a + b)² = a² + 2ab + b² to find 102².
  26. 26.Use (a + b)(a − b) = a² − b² to find 55 × 45.
  27. 27.Use (a − b)² = a² − 2ab + b² to find 88².
  28. 28.Use (a + b)(a − b) = a² − b² to find 33 × 27.
  29. 29.Find the value of x² + 2xy + y² when x = 11 and y = 3.
  30. 30.Use (a + b)² = a² + 2ab + b² to find 36².
  31. 31.Use (a + b)² = a² + 2ab + b² to find 43².
  32. 32.Find the value of x² − 2xy + y² when x = 7 and y = 3.
  33. 33.Use (a + b)² = a² + 2ab + b² to find 93².
  34. 34.Use (a + b)(a − b) = a² − b² to find 66 × 54.
  35. 35.Use a² − b² = (a + b)(a − b) to find 51² − 32².
  36. 36.Find the value of x² − y² when x = 15 and y = 5.
  37. 37.Use a² − b² = (a + b)(a − b) to find 40² − 2².
  38. 38.If a + b = 10 and ab = 16, what is a² + b²?
  39. 39.If a + b = 14 and ab = 45, what is a² + b²?
  40. 40.Use (a − b)² = a² − 2ab + b² to find 89².

Answer key

  1. 13
  2. 121
  3. 2601
  4. 8036
  5. 9604
  6. 1375
  7. 41
  8. 6336
  9. 3536
  10. 6561
  11. 448
  12. 144
  13. 1521
  14. 5
  15. 4489
  16. 10201
  17. 3551
  18. 528
  19. 26
  20. 4
  21. 8084
  22. 1
  23. 136
  24. 65
  25. 10404
  26. 2475
  27. 7744
  28. 891
  29. 196
  30. 1296
  31. 1849
  32. 16
  33. 8649
  34. 3564
  35. 1577
  36. 200
  37. 1596
  38. 68
  39. 106
  40. 7921

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