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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 863 · 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 93².
  2. 2.Find the value of x² + 2xy + y² when x = 14 and y = 8.
  3. 3.Use (a − b)² = a² − 2ab + b² to find 38².
  4. 4.If a − b = 5 and ab = 6, what is a² + b²?
  5. 5.Use (a + b)(a − b) = a² − b² to find 67 × 53.
  6. 6.If a − b = 2 and ab = 8, what is a² + b²?
  7. 7.Use (a + b)(a − b) = a² − b² to find 81 × 79.
  8. 8.If a + b = 8 and ab = 7, what is a² + b²?
  9. 9.Use (a + b)² = a² + 2ab + b² to find 86².
  10. 10.Find the value of x² + 2xy + y² when x = 14 and y = 6.
  11. 11.Use (a + b)(a − b) = a² − b² to find 77 × 63.
  12. 12.Use (a + b)(a − b) = a² − b² to find 22 × 18.
  13. 13.If a − b = 6 and ab = 72, what is a² + b²?
  14. 14.Find the value of x² − y² when x = 5 and y = 3.
  15. 15.Find the value of x² − 2xy + y² when x = 11 and y = 8.
  16. 16.Use (a + b)(a − b) = a² − b² to find 74 × 66.
  17. 17.Use (a + b)² = a² + 2ab + b² to find 99².
  18. 18.Use a² − b² = (a + b)(a − b) to find 98² − 20².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 42².
  20. 20.Use a² − b² = (a + b)(a − b) to find 66² − 19².
  21. 21.If a + b = 15 and ab = 56, what is a² + b²?
  22. 22.If a + b = 13 and ab = 40, what is a² + b²?
  23. 23.Find the value of x² + 2xy + y² when x = 9 and y = 1.
  24. 24.Use (a + b)(a − b) = a² − b² to find 56 × 44.
  25. 25.Find the value of x² + 2xy + y² when x = 12 and y = 4.
  26. 26.Find the value of x² − 2xy + y² when x = 15 and y = 9.
  27. 27.Find the value of x² − y² when x = 5 and y = 1.
  28. 28.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  29. 29.Use a² − b² = (a + b)(a − b) to find 73² − 41².
  30. 30.Use (a + b)(a − b) = a² − b² to find 39 × 21.
  31. 31.Use (a − b)² = a² − 2ab + b² to find 94².
  32. 32.Use a² − b² = (a + b)(a − b) to find 87² − 41².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 17².
  34. 34.Find the value of x² − 2xy + y² when x = 12 and y = 10.
  35. 35.Use (a − b)² = a² − 2ab + b² to find 61².
  36. 36.Use a² − b² = (a + b)(a − b) to find 74² − 63².
  37. 37.If a + b = 5 and ab = 6, what is a² + b²?
  38. 38.Use (a − b)² = a² − 2ab + b² to find 76².
  39. 39.Use (a + b)(a − b) = a² − b² to find 86 × 74.
  40. 40.Use (a − b)² = a² − 2ab + b² to find 19².

Answer key

  1. 8649
  2. 484
  3. 1444
  4. 37
  5. 3551
  6. 20
  7. 6399
  8. 50
  9. 7396
  10. 400
  11. 4851
  12. 396
  13. 180
  14. 16
  15. 9
  16. 4884
  17. 9801
  18. 9204
  19. 1764
  20. 3995
  21. 113
  22. 89
  23. 100
  24. 2464
  25. 256
  26. 36
  27. 24
  28. 25
  29. 3648
  30. 819
  31. 8836
  32. 5888
  33. 289
  34. 4
  35. 3721
  36. 1507
  37. 13
  38. 5776
  39. 6364
  40. 361

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