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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 97 · 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 = 2 and ab = 35, what is a² + b²?
  2. 2.Use a² − b² = (a + b)(a − b) to find 34² − 13².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 88².
  4. 4.Find the value of x² − y² when x = 15 and y = 7.
  5. 5.Use (a + b)² = a² + 2ab + b² to find 16².
  6. 6.Use a² − b² = (a + b)(a − b) to find 67² − 33².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 92².
  8. 8.Use (a + b)² = a² + 2ab + b² to find 101².
  9. 9.Use (a − b)² = a² − 2ab + b² to find 45².
  10. 10.If a − b = 1 and ab = 6, what is a² + b²?
  11. 11.Use (a + b)(a − b) = a² − b² to find 104 × 96.
  12. 12.If a − b = 10 and ab = 24, what is a² + b²?
  13. 13.Use (a − b)² = a² − 2ab + b² to find 53².
  14. 14.Use (a + b)² = a² + 2ab + b² to find 105².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 12².
  16. 16.Use a² − b² = (a + b)(a − b) to find 22² − 9².
  17. 17.Find the value of x² − y² when x = 4 and y = 1.
  18. 18.Use (a + b)² = a² + 2ab + b² to find 47².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 28².
  20. 20.If a − b = 5 and ab = 36, what is a² + b²?
  21. 21.Use a² − b² = (a + b)(a − b) to find 49² − 18².
  22. 22.Find the value of x² + 2xy + y² when x = 5 and y = 3.
  23. 23.If a + b = 9 and ab = 20, what is a² + b²?
  24. 24.Use (a + b)(a − b) = a² − b² to find 53 × 47.
  25. 25.Use a² − b² = (a + b)(a − b) to find 96² − 40².
  26. 26.Use (a + b)² = a² + 2ab + b² to find 87².
  27. 27.Use (a + b)² = a² + 2ab + b² to find 86².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 99².
  29. 29.Find the value of x² − y² when x = 3 and y = 2.
  30. 30.Use (a − b)² = a² − 2ab + b² to find 16².
  31. 31.Use (a + b)² = a² + 2ab + b² to find 75².
  32. 32.Use a² − b² = (a + b)(a − b) to find 96² − 79².
  33. 33.If a − b = 2 and ab = 3, what is a² + b²?
  34. 34.Use a² − b² = (a + b)(a − b) to find 50² − 36².
  35. 35.Use (a + b)² = a² + 2ab + b² to find 43².
  36. 36.Use (a + b)² = a² + 2ab + b² to find 69².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 64².
  38. 38.If a − b = 8 and ab = 9, what is a² + b²?
  39. 39.Find the value of x² − 2xy + y² when x = 5 and y = 4.
  40. 40.Use (a + b)(a − b) = a² − b² to find 91 × 89.

Answer key

  1. 74
  2. 987
  3. 7744
  4. 176
  5. 256
  6. 3400
  7. 8464
  8. 10201
  9. 2025
  10. 13
  11. 9984
  12. 148
  13. 2809
  14. 11025
  15. 144
  16. 403
  17. 15
  18. 2209
  19. 784
  20. 97
  21. 2077
  22. 64
  23. 41
  24. 2491
  25. 7616
  26. 7569
  27. 7396
  28. 9801
  29. 5
  30. 256
  31. 5625
  32. 2975
  33. 10
  34. 1204
  35. 1849
  36. 4761
  37. 4096
  38. 82
  39. 1
  40. 8099

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