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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 682 · 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 35².
  2. 2.Use (a − b)² = a² − 2ab + b² to find 37².
  3. 3.Find the value of x² − y² when x = 5 and y = 3.
  4. 4.Use (a − b)² = a² − 2ab + b² to find 92².
  5. 5.If a − b = 1 and ab = 2, what is a² + b²?
  6. 6.Use (a + b)(a − b) = a² − b² to find 95 × 85.
  7. 7.Use (a − b)² = a² − 2ab + b² to find 79².
  8. 8.Use (a + b)(a − b) = a² − b² to find 98 × 82.
  9. 9.Find the value of x² + 2xy + y² when x = 12 and y = 4.
  10. 10.Use (a + b)² = a² + 2ab + b² to find 75².
  11. 11.Use (a + b)² = a² + 2ab + b² to find 105².
  12. 12.Use (a + b)² = a² + 2ab + b² to find 56².
  13. 13.Find the value of x² + 2xy + y² when x = 7 and y = 5.
  14. 14.Find the value of x² − y² when x = 3 and y = 1.
  15. 15.Use (a − b)² = a² − 2ab + b² to find 43².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 86².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 62².
  18. 18.Find the value of x² − 2xy + y² when x = 6 and y = 5.
  19. 19.Find the value of x² − 2xy + y² when x = 4 and y = 1.
  20. 20.Use a² − b² = (a + b)(a − b) to find 41² − 9².
  21. 21.Use (a − b)² = a² − 2ab + b² to find 28².
  22. 22.Use (a + b)² = a² + 2ab + b² to find 23².
  23. 23.Find the value of x² − y² when x = 11 and y = 5.
  24. 24.Use (a + b)² = a² + 2ab + b² to find 61².
  25. 25.Use a² − b² = (a + b)(a − b) to find 60² − 2².
  26. 26.Use (a − b)² = a² − 2ab + b² to find 97².
  27. 27.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  28. 28.Find the value of x² − 2xy + y² when x = 14 and y = 2.
  29. 29.Find the value of x² − y² when x = 15 and y = 14.
  30. 30.Use (a + b)(a − b) = a² − b² to find 27 × 13.
  31. 31.Use (a + b)² = a² + 2ab + b² to find 91².
  32. 32.If a + b = 9 and ab = 8, what is a² + b²?
  33. 33.Use (a + b)² = a² + 2ab + b² to find 77².
  34. 34.Use (a + b)(a − b) = a² − b² to find 44 × 36.
  35. 35.Use a² − b² = (a + b)(a − b) to find 20² − 2².
  36. 36.Find the value of x² − y² when x = 14 and y = 2.
  37. 37.Use a² − b² = (a + b)(a − b) to find 73² − 7².
  38. 38.If a − b = 7 and ab = 30, what is a² + b²?
  39. 39.If a − b = 6 and ab = 27, what is a² + b²?
  40. 40.Use (a + b)(a − b) = a² − b² to find 47 × 33.

Answer key

  1. 1225
  2. 1369
  3. 16
  4. 8464
  5. 5
  6. 8075
  7. 6241
  8. 8036
  9. 256
  10. 5625
  11. 11025
  12. 3136
  13. 144
  14. 8
  15. 1849
  16. 7396
  17. 3844
  18. 1
  19. 9
  20. 1600
  21. 784
  22. 529
  23. 96
  24. 3721
  25. 3596
  26. 9409
  27. 25
  28. 144
  29. 29
  30. 351
  31. 8281
  32. 65
  33. 5929
  34. 1584
  35. 396
  36. 192
  37. 5280
  38. 109
  39. 90
  40. 1551

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