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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 798 · 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 103 × 97.
  2. 2.If a − b = 5 and ab = 66, what is a² + b²?
  3. 3.Use (a − b)² = a² − 2ab + b² to find 46².
  4. 4.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  5. 5.Find the value of x² − y² when x = 7 and y = 1.
  6. 6.Find the value of x² + 2xy + y² when x = 13 and y = 12.
  7. 7.Use (a − b)² = a² − 2ab + b² to find 59².
  8. 8.Find the value of x² − y² when x = 7 and y = 5.
  9. 9.Use (a + b)² = a² + 2ab + b² to find 47².
  10. 10.Use a² − b² = (a + b)(a − b) to find 45² − 13².
  11. 11.Use (a + b)² = a² + 2ab + b² to find 36².
  12. 12.Use (a + b)² = a² + 2ab + b² to find 87².
  13. 13.If a − b = 1 and ab = 2, what is a² + b²?
  14. 14.Use (a + b)(a − b) = a² − b² to find 73 × 67.
  15. 15.If a − b = 7 and ab = 44, what is a² + b²?
  16. 16.Use (a − b)² = a² − 2ab + b² to find 37².
  17. 17.Use a² − b² = (a + b)(a − b) to find 78² − 6².
  18. 18.If a + b = 23 and ab = 132, what is a² + b²?
  19. 19.Use (a − b)² = a² − 2ab + b² to find 76².
  20. 20.Use (a + b)² = a² + 2ab + b² to find 103².
  21. 21.Find the value of x² + 2xy + y² when x = 11 and y = 1.
  22. 22.If a − b = 5 and ab = 6, what is a² + b²?
  23. 23.Use (a − b)² = a² − 2ab + b² to find 65².
  24. 24.Use a² − b² = (a + b)(a − b) to find 55² − 46².
  25. 25.Use (a + b)(a − b) = a² − b² to find 95 × 85.
  26. 26.If a + b = 6 and ab = 5, what is a² + b²?
  27. 27.Use (a + b)² = a² + 2ab + b² to find 61².
  28. 28.Find the value of x² − 2xy + y² when x = 10 and y = 9.
  29. 29.Find the value of x² − y² when x = 4 and y = 3.
  30. 30.Use a² − b² = (a + b)(a − b) to find 43² − 3².
  31. 31.If a + b = 6 and ab = 8, what is a² + b²?
  32. 32.Use a² − b² = (a + b)(a − b) to find 87² − 22².
  33. 33.Use (a + b)(a − b) = a² − b² to find 67 × 53.
  34. 34.Use (a − b)² = a² − 2ab + b² to find 66².
  35. 35.Find the value of x² + 2xy + y² when x = 11 and y = 9.
  36. 36.Find the value of x² − y² when x = 11 and y = 1.
  37. 37.Find the value of x² − y² when x = 6 and y = 5.
  38. 38.Use (a + b)² = a² + 2ab + b² to find 85².
  39. 39.Use a² − b² = (a + b)(a − b) to find 71² − 14².
  40. 40.Use (a + b)² = a² + 2ab + b² to find 66².

Answer key

  1. 9991
  2. 157
  3. 2116
  4. 25
  5. 48
  6. 625
  7. 3481
  8. 24
  9. 2209
  10. 1856
  11. 1296
  12. 7569
  13. 5
  14. 4891
  15. 137
  16. 1369
  17. 6048
  18. 265
  19. 5776
  20. 10609
  21. 144
  22. 37
  23. 4225
  24. 909
  25. 8075
  26. 26
  27. 3721
  28. 1
  29. 7
  30. 1840
  31. 20
  32. 7085
  33. 3551
  34. 4356
  35. 400
  36. 120
  37. 11
  38. 7225
  39. 4845
  40. 4356

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