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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 894 · 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 102².
  2. 2.If a + b = 3 and ab = 2, what is a² + b²?
  3. 3.Use (a + b)(a − b) = a² − b² to find 76 × 64.
  4. 4.Use (a + b)² = a² + 2ab + b² to find 28².
  5. 5.Use (a − b)² = a² − 2ab + b² to find 57².
  6. 6.Use (a + b)(a − b) = a² − b² to find 106 × 94.
  7. 7.Find the value of x² + 2xy + y² when x = 6 and y = 2.
  8. 8.Use (a + b)(a − b) = a² − b² to find 46 × 34.
  9. 9.Use (a + b)(a − b) = a² − b² to find 66 × 54.
  10. 10.Find the value of x² − y² when x = 6 and y = 2.
  11. 11.Use (a − b)² = a² − 2ab + b² to find 76².
  12. 12.Use (a + b)² = a² + 2ab + b² to find 37².
  13. 13.Use (a + b)² = a² + 2ab + b² to find 85².
  14. 14.If a + b = 7 and ab = 10, what is a² + b²?
  15. 15.Use (a − b)² = a² − 2ab + b² to find 18².
  16. 16.Use a² − b² = (a + b)(a − b) to find 32² − 7².
  17. 17.Find the value of x² − 2xy + y² when x = 4 and y = 2.
  18. 18.Use (a + b)(a − b) = a² − b² to find 22 × 18.
  19. 19.Use (a − b)² = a² − 2ab + b² to find 88².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 22².
  21. 21.Use (a + b)(a − b) = a² − b² to find 21 × 19.
  22. 22.If a − b = 5 and ab = 6, what is a² + b²?
  23. 23.Use (a − b)² = a² − 2ab + b² to find 43².
  24. 24.If a + b = 17 and ab = 70, what is a² + b²?
  25. 25.Use (a − b)² = a² − 2ab + b² to find 36².
  26. 26.Use a² − b² = (a + b)(a − b) to find 25² − 10².
  27. 27.Use (a − b)² = a² − 2ab + b² to find 66².
  28. 28.Use (a − b)² = a² − 2ab + b² to find 12².
  29. 29.Use (a + b)(a − b) = a² − b² to find 82 × 78.
  30. 30.Use (a − b)² = a² − 2ab + b² to find 68².
  31. 31.Use (a + b)(a − b) = a² − b² to find 55 × 45.
  32. 32.Use a² − b² = (a + b)(a − b) to find 33² − 10².
  33. 33.Use (a − b)² = a² − 2ab + b² to find 99².
  34. 34.Use (a + b)(a − b) = a² − b² to find 95 × 85.
  35. 35.Use (a + b)² = a² + 2ab + b² to find 81².
  36. 36.If a − b = 1 and ab = 6, what is a² + b²?
  37. 37.Use (a + b)² = a² + 2ab + b² to find 49².
  38. 38.Find the value of x² − y² when x = 6 and y = 1.
  39. 39.Use (a + b)² = a² + 2ab + b² to find 88².
  40. 40.Find the value of x² + 2xy + y² when x = 6 and y = 4.

Answer key

  1. 10404
  2. 5
  3. 4864
  4. 784
  5. 3249
  6. 9964
  7. 64
  8. 1564
  9. 3564
  10. 32
  11. 5776
  12. 1369
  13. 7225
  14. 29
  15. 324
  16. 975
  17. 4
  18. 396
  19. 7744
  20. 484
  21. 399
  22. 37
  23. 1849
  24. 149
  25. 1296
  26. 525
  27. 4356
  28. 144
  29. 6396
  30. 4624
  31. 2475
  32. 989
  33. 9801
  34. 8075
  35. 6561
  36. 13
  37. 2401
  38. 35
  39. 7744
  40. 100

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