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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 303 · 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.Use (a + b)(a − b) = a² − b² to find 59 × 41.
  2. 2.If a − b = 1 and ab = 2, what is a² + b²?
  3. 3.Use (a + b)² = a² + 2ab + b² to find 15².
  4. 4.Use a² − b² = (a + b)(a − b) to find 28² − 26².
  5. 5.Use (a + b)² = a² + 2ab + b² to find 69².
  6. 6.Use a² − b² = (a + b)(a − b) to find 83² − 55².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 22².
  8. 8.Find the value of x² − 2xy + y² when x = 12 and y = 5.
  9. 9.If a − b = 3 and ab = 10, what is a² + b²?
  10. 10.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  11. 11.If a + b = 5 and ab = 4, what is a² + b²?
  12. 12.If a − b = 1 and ab = 6, what is a² + b²?
  13. 13.If a + b = 5 and ab = 6, what is a² + b²?
  14. 14.If a + b = 12 and ab = 35, what is a² + b²?
  15. 15.Use (a + b)(a − b) = a² − b² to find 96 × 84.
  16. 16.Find the value of x² + 2xy + y² when x = 14 and y = 2.
  17. 17.Use (a + b)² = a² + 2ab + b² to find 58².
  18. 18.Find the value of x² − y² when x = 13 and y = 8.
  19. 19.Find the value of x² − y² when x = 13 and y = 4.
  20. 20.Use (a − b)² = a² − 2ab + b² to find 22².
  21. 21.If a − b = 3 and ab = 40, what is a² + b²?
  22. 22.Use (a + b)(a − b) = a² − b² to find 52 × 48.
  23. 23.Use a² − b² = (a + b)(a − b) to find 25² − 13².
  24. 24.Use (a + b)(a − b) = a² − b² to find 34 × 26.
  25. 25.Find the value of x² + 2xy + y² when x = 11 and y = 1.
  26. 26.Use (a − b)² = a² − 2ab + b² to find 15².
  27. 27.Use (a + b)² = a² + 2ab + b² to find 55².
  28. 28.Use a² − b² = (a + b)(a − b) to find 81² − 61².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 33².
  30. 30.Use (a − b)² = a² − 2ab + b² to find 23².
  31. 31.Use a² − b² = (a + b)(a − b) to find 33² − 32².
  32. 32.Use (a − b)² = a² − 2ab + b² to find 67².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 92².
  34. 34.Use a² − b² = (a + b)(a − b) to find 25² − 2².
  35. 35.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  36. 36.Find the value of x² + 2xy + y² when x = 8 and y = 6.
  37. 37.Use (a − b)² = a² − 2ab + b² to find 42².
  38. 38.Use (a + b)(a − b) = a² − b² to find 24 × 16.
  39. 39.Use (a − b)² = a² − 2ab + b² to find 93².
  40. 40.Use (a + b)(a − b) = a² − b² to find 42 × 38.

Answer key

  1. 2419
  2. 5
  3. 225
  4. 108
  5. 4761
  6. 3864
  7. 484
  8. 49
  9. 29
  10. 1591
  11. 17
  12. 13
  13. 13
  14. 74
  15. 8064
  16. 256
  17. 3364
  18. 105
  19. 153
  20. 484
  21. 89
  22. 2496
  23. 456
  24. 884
  25. 144
  26. 225
  27. 3025
  28. 2840
  29. 1089
  30. 529
  31. 65
  32. 4489
  33. 8464
  34. 621
  35. 899
  36. 196
  37. 1764
  38. 384
  39. 8649
  40. 1596

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