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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 151 · 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)(a − b) = a² − b² to find 106 × 94.
  2. 2.Use (a + b)(a − b) = a² − b² to find 26 × 14.
  3. 3.Use (a − b)² = a² − 2ab + b² to find 11².
  4. 4.Use (a + b)(a − b) = a² − b² to find 66 × 54.
  5. 5.Use (a + b)² = a² + 2ab + b² to find 62².
  6. 6.If a + b = 9 and ab = 20, what is a² + b²?
  7. 7.Use (a + b)(a − b) = a² − b² to find 101 × 99.
  8. 8.Find the value of x² − 2xy + y² when x = 13 and y = 5.
  9. 9.Use (a + b)(a − b) = a² − b² to find 84 × 76.
  10. 10.If a + b = 8 and ab = 7, what is a² + b²?
  11. 11.Find the value of x² − y² when x = 3 and y = 1.
  12. 12.Use (a − b)² = a² − 2ab + b² to find 69².
  13. 13.Find the value of x² + 2xy + y² when x = 7 and y = 5.
  14. 14.Use (a + b)² = a² + 2ab + b² to find 81².
  15. 15.If a + b = 6 and ab = 8, what is a² + b²?
  16. 16.Use a² − b² = (a + b)(a − b) to find 59² − 6².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 35².
  18. 18.Use a² − b² = (a + b)(a − b) to find 49² − 29².
  19. 19.If a − b = 3 and ab = 108, what is a² + b²?
  20. 20.Use (a + b)² = a² + 2ab + b² to find 75².
  21. 21.Use (a − b)² = a² − 2ab + b² to find 12².
  22. 22.If a − b = 3 and ab = 4, what is a² + b²?
  23. 23.Use (a − b)² = a² − 2ab + b² to find 42².
  24. 24.Use a² − b² = (a + b)(a − b) to find 29² − 10².
  25. 25.Find the value of x² + 2xy + y² when x = 13 and y = 8.
  26. 26.Use a² − b² = (a + b)(a − b) to find 60² − 38².
  27. 27.If a + b = 15 and ab = 36, what is a² + b²?
  28. 28.Use (a + b)² = a² + 2ab + b² to find 98².
  29. 29.Find the value of x² − y² when x = 14 and y = 13.
  30. 30.Use a² − b² = (a + b)(a − b) to find 99² − 76².
  31. 31.Use (a − b)² = a² − 2ab + b² to find 83².
  32. 32.If a + b = 3 and ab = 2, what is a² + b²?
  33. 33.Use (a − b)² = a² − 2ab + b² to find 84².
  34. 34.Use (a + b)(a − b) = a² − b² to find 92 × 88.
  35. 35.Use (a − b)² = a² − 2ab + b² to find 96².
  36. 36.Find the value of x² + 2xy + y² when x = 5 and y = 1.
  37. 37.Use a² − b² = (a + b)(a − b) to find 51² − 40².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 63².
  39. 39.Use (a + b)(a − b) = a² − b² to find 52 × 48.
  40. 40.Use a² − b² = (a + b)(a − b) to find 74² − 58².

Answer key

  1. 9964
  2. 364
  3. 121
  4. 3564
  5. 3844
  6. 41
  7. 9999
  8. 64
  9. 6384
  10. 50
  11. 8
  12. 4761
  13. 144
  14. 6561
  15. 20
  16. 3445
  17. 1225
  18. 1560
  19. 225
  20. 5625
  21. 144
  22. 17
  23. 1764
  24. 741
  25. 441
  26. 2156
  27. 153
  28. 9604
  29. 27
  30. 4025
  31. 6889
  32. 5
  33. 7056
  34. 8096
  35. 9216
  36. 36
  37. 1001
  38. 3969
  39. 2496
  40. 2112

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