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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 56 · 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 101².
  2. 2.Use a² − b² = (a + b)(a − b) to find 52² − 31².
  3. 3.Use a² − b² = (a + b)(a − b) to find 23² − 18².
  4. 4.If a − b = 2 and ab = 63, what is a² + b²?
  5. 5.Use (a + b)² = a² + 2ab + b² to find 66².
  6. 6.Use (a + b)(a − b) = a² − b² to find 57 × 43.
  7. 7.Use (a − b)² = a² − 2ab + b² to find 93².
  8. 8.If a − b = 1 and ab = 6, what is a² + b²?
  9. 9.Use (a + b)(a − b) = a² − b² to find 45 × 35.
  10. 10.Use (a − b)² = a² − 2ab + b² to find 71².
  11. 11.Use (a + b)² = a² + 2ab + b² to find 24².
  12. 12.Find the value of x² − 2xy + y² when x = 9 and y = 8.
  13. 13.If a + b = 3 and ab = 2, what is a² + b²?
  14. 14.Use (a − b)² = a² − 2ab + b² to find 52².
  15. 15.Use (a + b)² = a² + 2ab + b² to find 63².
  16. 16.If a + b = 4 and ab = 3, what is a² + b²?
  17. 17.Find the value of x² + 2xy + y² when x = 9 and y = 6.
  18. 18.Use a² − b² = (a + b)(a − b) to find 26² − 19².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 36².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 57².
  21. 21.Use (a + b)(a − b) = a² − b² to find 72 × 68.
  22. 22.Use (a + b)(a − b) = a² − b² to find 82 × 78.
  23. 23.Find the value of x² + 2xy + y² when x = 10 and y = 9.
  24. 24.If a + b = 5 and ab = 4, what is a² + b²?
  25. 25.If a − b = 4 and ab = 5, what is a² + b²?
  26. 26.Find the value of x² − y² when x = 10 and y = 7.
  27. 27.Find the value of x² − y² when x = 8 and y = 5.
  28. 28.Use (a − b)² = a² − 2ab + b² to find 65².
  29. 29.Use (a − b)² = a² − 2ab + b² to find 34².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 43².
  31. 31.Use (a + b)(a − b) = a² − b² to find 92 × 88.
  32. 32.Use (a + b)² = a² + 2ab + b² to find 102².
  33. 33.Use (a − b)² = a² − 2ab + b² to find 75².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 88².
  35. 35.Find the value of x² − y² when x = 4 and y = 3.
  36. 36.If a − b = 1 and ab = 2, what is a² + b²?
  37. 37.Use (a + b)(a − b) = a² − b² to find 32 × 28.
  38. 38.If a + b = 12 and ab = 32, what is a² + b²?
  39. 39.Use (a + b)² = a² + 2ab + b² to find 51².
  40. 40.Use a² − b² = (a + b)(a − b) to find 52² − 2².

Answer key

  1. 10201
  2. 1743
  3. 205
  4. 130
  5. 4356
  6. 2451
  7. 8649
  8. 13
  9. 1575
  10. 5041
  11. 576
  12. 1
  13. 5
  14. 2704
  15. 3969
  16. 10
  17. 225
  18. 315
  19. 1296
  20. 3249
  21. 4896
  22. 6396
  23. 361
  24. 17
  25. 26
  26. 51
  27. 39
  28. 4225
  29. 1156
  30. 1849
  31. 8096
  32. 10404
  33. 5625
  34. 7744
  35. 7
  36. 5
  37. 896
  38. 80
  39. 2601
  40. 2700

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