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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 684 · 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 51².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 13².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 28².
  4. 4.Find the value of x² − 2xy + y² when x = 6 and y = 1.
  5. 5.If a − b = 1 and ab = 2, what is a² + b²?
  6. 6.Use (a − b)² = a² − 2ab + b² to find 29².
  7. 7.Use (a + b)(a − b) = a² − b² to find 55 × 45.
  8. 8.Use (a + b)(a − b) = a² − b² to find 81 × 79.
  9. 9.Use (a + b)² = a² + 2ab + b² to find 62².
  10. 10.Use (a + b)² = a² + 2ab + b² to find 86².
  11. 11.Use (a + b)² = a² + 2ab + b² to find 29².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 88².
  13. 13.If a − b = 2 and ab = 8, what is a² + b²?
  14. 14.If a + b = 13 and ab = 40, what is a² + b²?
  15. 15.If a − b = 4 and ab = 45, what is a² + b²?
  16. 16.Use (a + b)(a − b) = a² − b² to find 47 × 33.
  17. 17.Use (a − b)² = a² − 2ab + b² to find 32².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 58².
  19. 19.If a + b = 14 and ab = 33, what is a² + b²?
  20. 20.Use (a + b)² = a² + 2ab + b² to find 74².
  21. 21.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  22. 22.Use (a + b)(a − b) = a² − b² to find 74 × 66.
  23. 23.Find the value of x² − y² when x = 5 and y = 4.
  24. 24.Use (a + b)(a − b) = a² − b² to find 71 × 69.
  25. 25.Use (a + b)² = a² + 2ab + b² to find 36².
  26. 26.Use (a − b)² = a² − 2ab + b² to find 35².
  27. 27.If a + b = 5 and ab = 6, what is a² + b²?
  28. 28.If a − b = 6 and ab = 16, what is a² + b²?
  29. 29.Use (a + b)² = a² + 2ab + b² to find 44².
  30. 30.Use a² − b² = (a + b)(a − b) to find 93² − 67².
  31. 31.Use (a + b)² = a² + 2ab + b² to find 82².
  32. 32.Use (a + b)² = a² + 2ab + b² to find 37².
  33. 33.Use (a − b)² = a² − 2ab + b² to find 19².
  34. 34.Use a² − b² = (a + b)(a − b) to find 26² − 25².
  35. 35.Find the value of x² + 2xy + y² when x = 14 and y = 5.
  36. 36.Find the value of x² + 2xy + y² when x = 12 and y = 11.
  37. 37.If a + b = 16 and ab = 55, what is a² + b²?
  38. 38.Use a² − b² = (a + b)(a − b) to find 54² − 10².
  39. 39.Find the value of x² + 2xy + y² when x = 4 and y = 3.
  40. 40.Use (a + b)(a − b) = a² − b² to find 24 × 16.

Answer key

  1. 2601
  2. 169
  3. 784
  4. 25
  5. 5
  6. 841
  7. 2475
  8. 6399
  9. 3844
  10. 7396
  11. 841
  12. 7744
  13. 20
  14. 89
  15. 106
  16. 1551
  17. 1024
  18. 3364
  19. 130
  20. 5476
  21. 25
  22. 4884
  23. 9
  24. 4899
  25. 1296
  26. 1225
  27. 13
  28. 68
  29. 1936
  30. 4160
  31. 6724
  32. 1369
  33. 361
  34. 51
  35. 361
  36. 529
  37. 146
  38. 2816
  39. 49
  40. 384

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