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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 104 · 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.If a − b = 10 and ab = 24, what is a² + b²?
  2. 2.Use (a + b)(a − b) = a² − b² to find 103 × 97.
  3. 3.Find the value of x² − y² when x = 11 and y = 6.
  4. 4.Use (a − b)² = a² − 2ab + b² to find 35².
  5. 5.Find the value of x² − 2xy + y² when x = 7 and y = 3.
  6. 6.If a − b = 3 and ab = 10, what is a² + b²?
  7. 7.Use (a + b)(a − b) = a² − b² to find 99 × 81.
  8. 8.Use (a + b)(a − b) = a² − b² to find 104 × 96.
  9. 9.Use a² − b² = (a + b)(a − b) to find 42² − 34².
  10. 10.Find the value of x² + 2xy + y² when x = 9 and y = 8.
  11. 11.Use a² − b² = (a + b)(a − b) to find 96² − 79².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 37².
  13. 13.If a − b = 2 and ab = 120, what is a² + b²?
  14. 14.Use a² − b² = (a + b)(a − b) to find 96² − 36².
  15. 15.Use a² − b² = (a + b)(a − b) to find 31² − 22².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 24².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 73².
  18. 18.Use a² − b² = (a + b)(a − b) to find 23² − 21².
  19. 19.Use (a − b)² = a² − 2ab + b² to find 91².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 17².
  21. 21.Use (a − b)² = a² − 2ab + b² to find 55².
  22. 22.Use (a + b)(a − b) = a² − b² to find 61 × 59.
  23. 23.Find the value of x² + 2xy + y² when x = 15 and y = 4.
  24. 24.Use (a + b)² = a² + 2ab + b² to find 102².
  25. 25.Use (a + b)(a − b) = a² − b² to find 71 × 69.
  26. 26.Use (a − b)² = a² − 2ab + b² to find 22².
  27. 27.If a + b = 3 and ab = 2, what is a² + b²?
  28. 28.Use a² − b² = (a + b)(a − b) to find 32² − 13².
  29. 29.Use a² − b² = (a + b)(a − b) to find 54² − 30².
  30. 30.Find the value of x² + 2xy + y² when x = 10 and y = 5.
  31. 31.Use a² − b² = (a + b)(a − b) to find 55² − 34².
  32. 32.Find the value of x² + 2xy + y² when x = 5 and y = 4.
  33. 33.If a + b = 16 and ab = 55, what is a² + b²?
  34. 34.Use (a + b)² = a² + 2ab + b² to find 65².
  35. 35.Use (a + b)(a − b) = a² − b² to find 98 × 82.
  36. 36.Use (a − b)² = a² − 2ab + b² to find 69².
  37. 37.Use a² − b² = (a + b)(a − b) to find 42² − 6².
  38. 38.Use (a + b)(a − b) = a² − b² to find 79 × 61.
  39. 39.Use (a + b)(a − b) = a² − b² to find 109 × 91.
  40. 40.Use (a − b)² = a² − 2ab + b² to find 59².

Answer key

  1. 148
  2. 9991
  3. 85
  4. 1225
  5. 16
  6. 29
  7. 8019
  8. 9984
  9. 608
  10. 289
  11. 2975
  12. 1369
  13. 244
  14. 7920
  15. 477
  16. 576
  17. 5329
  18. 88
  19. 8281
  20. 289
  21. 3025
  22. 3599
  23. 361
  24. 10404
  25. 4899
  26. 484
  27. 5
  28. 855
  29. 2016
  30. 225
  31. 1869
  32. 81
  33. 146
  34. 4225
  35. 8036
  36. 4761
  37. 1728
  38. 4819
  39. 9919
  40. 3481

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