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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 617 · 40 sums
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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.Find the value of x² − y² when x = 4 and y = 3.
  2. 2.Find the value of x² + 2xy + y² when x = 10 and y = 7.
  3. 3.Find the value of x² − y² when x = 8 and y = 4.
  4. 4.Use (a + b)² = a² + 2ab + b² to find 93².
  5. 5.Use (a − b)² = a² − 2ab + b² to find 97².
  6. 6.If a + b = 5 and ab = 6, what is a² + b²?
  7. 7.Use (a − b)² = a² − 2ab + b² to find 26².
  8. 8.Find the value of x² + 2xy + y² when x = 13 and y = 7.
  9. 9.Use (a + b)² = a² + 2ab + b² to find 19².
  10. 10.Find the value of x² − y² when x = 15 and y = 1.
  11. 11.Use (a − b)² = a² − 2ab + b² to find 58².
  12. 12.Find the value of x² + 2xy + y² when x = 4 and y = 2.
  13. 13.Use (a − b)² = a² − 2ab + b² to find 27².
  14. 14.Use (a − b)² = a² − 2ab + b² to find 68².
  15. 15.If a + b = 10 and ab = 24, what is a² + b²?
  16. 16.Use a² − b² = (a + b)(a − b) to find 27² − 16².
  17. 17.Find the value of x² − 2xy + y² when x = 9 and y = 6.
  18. 18.Find the value of x² + 2xy + y² when x = 14 and y = 1.
  19. 19.Use a² − b² = (a + b)(a − b) to find 47² − 15².
  20. 20.Use (a + b)(a − b) = a² − b² to find 105 × 95.
  21. 21.Use (a − b)² = a² − 2ab + b² to find 35².
  22. 22.Use (a + b)(a − b) = a² − b² to find 64 × 56.
  23. 23.Use (a + b)² = a² + 2ab + b² to find 59².
  24. 24.Use (a − b)² = a² − 2ab + b² to find 81².
  25. 25.Use (a + b)(a − b) = a² − b² to find 92 × 88.
  26. 26.Use (a + b)² = a² + 2ab + b² to find 38².
  27. 27.Use (a + b)² = a² + 2ab + b² to find 72².
  28. 28.Use (a + b)(a − b) = a² − b² to find 93 × 87.
  29. 29.If a − b = 8 and ab = 9, what is a² + b²?
  30. 30.Find the value of x² − y² when x = 13 and y = 7.
  31. 31.Use (a + b)² = a² + 2ab + b² to find 92².
  32. 32.Use (a + b)² = a² + 2ab + b² to find 32².
  33. 33.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  34. 34.Use (a + b)(a − b) = a² − b² to find 37 × 23.
  35. 35.Find the value of x² − 2xy + y² when x = 13 and y = 6.
  36. 36.Use (a − b)² = a² − 2ab + b² to find 39².
  37. 37.Use a² − b² = (a + b)(a − b) to find 33² − 14².
  38. 38.Use (a + b)(a − b) = a² − b² to find 39 × 21.
  39. 39.Use (a + b)(a − b) = a² − b² to find 72 × 68.
  40. 40.Use (a − b)² = a² − 2ab + b² to find 31².

Answer key

  1. 7
  2. 289
  3. 48
  4. 8649
  5. 9409
  6. 13
  7. 676
  8. 400
  9. 361
  10. 224
  11. 3364
  12. 36
  13. 729
  14. 4624
  15. 52
  16. 473
  17. 9
  18. 225
  19. 1984
  20. 9975
  21. 1225
  22. 3584
  23. 3481
  24. 6561
  25. 8096
  26. 1444
  27. 5184
  28. 8091
  29. 82
  30. 120
  31. 8464
  32. 1024
  33. 1591
  34. 851
  35. 49
  36. 1521
  37. 893
  38. 819
  39. 4896
  40. 961

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