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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 442 · 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 a² − b² = (a + b)(a − b) to find 85² − 66².
  2. 2.Use a² − b² = (a + b)(a − b) to find 76² − 21².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 43².
  4. 4.Use a² − b² = (a + b)(a − b) to find 31² − 7².
  5. 5.Use (a + b)(a − b) = a² − b² to find 104 × 96.
  6. 6.Use a² − b² = (a + b)(a − b) to find 95² − 49².
  7. 7.Use (a − b)² = a² − 2ab + b² to find 19².
  8. 8.If a + b = 16 and ab = 48, what is a² + b²?
  9. 9.Find the value of x² − y² when x = 12 and y = 7.
  10. 10.Use (a + b)² = a² + 2ab + b² to find 24².
  11. 11.Use (a + b)² = a² + 2ab + b² to find 43².
  12. 12.Use (a + b)² = a² + 2ab + b² to find 92².
  13. 13.Use a² − b² = (a + b)(a − b) to find 35² − 8².
  14. 14.Use (a − b)² = a² − 2ab + b² to find 76².
  15. 15.Use (a + b)(a − b) = a² − b² to find 107 × 93.
  16. 16.Use (a + b)(a − b) = a² − b² to find 68 × 52.
  17. 17.If a − b = 1 and ab = 2, what is a² + b²?
  18. 18.Use (a + b)² = a² + 2ab + b² to find 62².
  19. 19.Find the value of x² − 2xy + y² when x = 11 and y = 10.
  20. 20.Use (a + b)(a − b) = a² − b² to find 75 × 65.
  21. 21.Use (a + b)² = a² + 2ab + b² to find 83².
  22. 22.Use a² − b² = (a + b)(a − b) to find 81² − 13².
  23. 23.Use (a + b)(a − b) = a² − b² to find 82 × 78.
  24. 24.Use a² − b² = (a + b)(a − b) to find 95² − 39².
  25. 25.Use (a + b)² = a² + 2ab + b² to find 38².
  26. 26.Use (a + b)² = a² + 2ab + b² to find 36².
  27. 27.Use (a + b)(a − b) = a² − b² to find 26 × 14.
  28. 28.Find the value of x² − 2xy + y² when x = 6 and y = 1.
  29. 29.Use (a − b)² = a² − 2ab + b² to find 68².
  30. 30.Use a² − b² = (a + b)(a − b) to find 30² − 16².
  31. 31.Find the value of x² + 2xy + y² when x = 8 and y = 5.
  32. 32.If a + b = 5 and ab = 6, what is a² + b²?
  33. 33.Find the value of x² + 2xy + y² when x = 6 and y = 4.
  34. 34.Use (a + b)(a − b) = a² − b² to find 24 × 16.
  35. 35.Find the value of x² + 2xy + y² when x = 12 and y = 8.
  36. 36.Find the value of x² + 2xy + y² when x = 3 and y = 1.
  37. 37.Find the value of x² + 2xy + y² when x = 8 and y = 4.
  38. 38.Find the value of x² + 2xy + y² when x = 9 and y = 4.
  39. 39.Use (a − b)² = a² − 2ab + b² to find 22².
  40. 40.If a + b = 8 and ab = 15, what is a² + b²?

Answer key

  1. 2869
  2. 5335
  3. 1849
  4. 912
  5. 9984
  6. 6624
  7. 361
  8. 160
  9. 95
  10. 576
  11. 1849
  12. 8464
  13. 1161
  14. 5776
  15. 9951
  16. 3536
  17. 5
  18. 3844
  19. 1
  20. 4875
  21. 6889
  22. 6392
  23. 6396
  24. 7504
  25. 1444
  26. 1296
  27. 364
  28. 25
  29. 4624
  30. 644
  31. 169
  32. 13
  33. 100
  34. 384
  35. 400
  36. 16
  37. 144
  38. 169
  39. 484
  40. 34

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