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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 903 · 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)² = a² − 2ab + b² to find 22².
  2. 2.Use a² − b² = (a + b)(a − b) to find 32² − 9².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 98².
  4. 4.Use (a − b)² = a² − 2ab + b² to find 31².
  5. 5.Find the value of x² − 2xy + y² when x = 7 and y = 4.
  6. 6.Use (a + b)(a − b) = a² − b² to find 63 × 57.
  7. 7.Use a² − b² = (a + b)(a − b) to find 70² − 29².
  8. 8.Use (a + b)² = a² + 2ab + b² to find 28².
  9. 9.Use (a + b)(a − b) = a² − b² to find 21 × 19.
  10. 10.If a + b = 12 and ab = 35, what is a² + b²?
  11. 11.Use (a + b)(a − b) = a² − b² to find 46 × 34.
  12. 12.Use (a + b)² = a² + 2ab + b² to find 38².
  13. 13.If a + b = 16 and ab = 63, what is a² + b²?
  14. 14.Use (a + b)² = a² + 2ab + b² to find 41².
  15. 15.If a + b = 4 and ab = 3, what is a² + b²?
  16. 16.Use (a − b)² = a² − 2ab + b² to find 57².
  17. 17.Use (a + b)(a − b) = a² − b² to find 72 × 68.
  18. 18.Use (a + b)² = a² + 2ab + b² to find 101².
  19. 19.If a − b = 1 and ab = 110, what is a² + b²?
  20. 20.Use (a − b)² = a² − 2ab + b² to find 99².
  21. 21.Use (a + b)(a − b) = a² − b² to find 82 × 78.
  22. 22.Use a² − b² = (a + b)(a − b) to find 76² − 2².
  23. 23.Use (a + b)² = a² + 2ab + b² to find 13².
  24. 24.Use (a − b)² = a² − 2ab + b² to find 64².
  25. 25.Use a² − b² = (a + b)(a − b) to find 45² − 12².
  26. 26.Use (a + b)² = a² + 2ab + b² to find 36².
  27. 27.Use a² − b² = (a + b)(a − b) to find 35² − 10².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 12².
  29. 29.Use (a + b)(a − b) = a² − b² to find 77 × 63.
  30. 30.Use (a − b)² = a² − 2ab + b² to find 37².
  31. 31.If a − b = 3 and ab = 28, what is a² + b²?
  32. 32.Use a² − b² = (a + b)(a − b) to find 27² − 14².
  33. 33.Use (a − b)² = a² − 2ab + b² to find 35².
  34. 34.Find the value of x² + 2xy + y² when x = 4 and y = 3.
  35. 35.Use (a + b)(a − b) = a² − b² to find 74 × 66.
  36. 36.Use a² − b² = (a + b)(a − b) to find 40² − 14².
  37. 37.Use (a + b)(a − b) = a² − b² to find 22 × 18.
  38. 38.Use a² − b² = (a + b)(a − b) to find 74² − 6².
  39. 39.If a + b = 8 and ab = 12, what is a² + b²?
  40. 40.Use (a + b)(a − b) = a² − b² to find 93 × 87.

Answer key

  1. 484
  2. 943
  3. 9604
  4. 961
  5. 9
  6. 3591
  7. 4059
  8. 784
  9. 399
  10. 74
  11. 1564
  12. 1444
  13. 130
  14. 1681
  15. 10
  16. 3249
  17. 4896
  18. 10201
  19. 221
  20. 9801
  21. 6396
  22. 5772
  23. 169
  24. 4096
  25. 1881
  26. 1296
  27. 1125
  28. 144
  29. 4851
  30. 1369
  31. 65
  32. 533
  33. 1225
  34. 49
  35. 4884
  36. 1404
  37. 396
  38. 5440
  39. 40
  40. 8091

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