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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 710 · 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.Find the value of x² + 2xy + y² when x = 14 and y = 11.
  2. 2.If a − b = 4 and ab = 5, what is a² + b²?
  3. 3.Use (a + b)² = a² + 2ab + b² to find 23².
  4. 4.Use (a − b)² = a² − 2ab + b² to find 39².
  5. 5.If a + b = 10 and ab = 16, what is a² + b²?
  6. 6.Use a² − b² = (a + b)(a − b) to find 70² − 51².
  7. 7.Use a² − b² = (a + b)(a − b) to find 31² − 11².
  8. 8.If a + b = 3 and ab = 2, what is a² + b²?
  9. 9.Use (a − b)² = a² − 2ab + b² to find 78².
  10. 10.Use (a − b)² = a² − 2ab + b² to find 84².
  11. 11.Use (a + b)² = a² + 2ab + b² to find 68².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 26².
  13. 13.Use (a + b)(a − b) = a² − b² to find 85 × 75.
  14. 14.If a − b = 3 and ab = 10, what is a² + b²?
  15. 15.Use (a + b)² = a² + 2ab + b² to find 93².
  16. 16.Find the value of x² − 2xy + y² when x = 7 and y = 6.
  17. 17.If a + b = 4 and ab = 3, what is a² + b²?
  18. 18.If a − b = 1 and ab = 2, what is a² + b²?
  19. 19.If a − b = 4 and ab = 12, what is a² + b²?
  20. 20.Use (a − b)² = a² − 2ab + b² to find 37².
  21. 21.Use a² − b² = (a + b)(a − b) to find 75² − 1².
  22. 22.Use (a + b)(a − b) = a² − b² to find 74 × 66.
  23. 23.Use (a + b)² = a² + 2ab + b² to find 43².
  24. 24.Use (a + b)(a − b) = a² − b² to find 28 × 12.
  25. 25.Use (a + b)² = a² + 2ab + b² to find 103².
  26. 26.Use (a + b)(a − b) = a² − b² to find 32 × 28.
  27. 27.Use a² − b² = (a + b)(a − b) to find 74² − 13².
  28. 28.Use (a − b)² = a² − 2ab + b² to find 88².
  29. 29.Use a² − b² = (a + b)(a − b) to find 76² − 52².
  30. 30.Find the value of x² − 2xy + y² when x = 15 and y = 9.
  31. 31.If a + b = 11 and ab = 30, what is a² + b²?
  32. 32.If a − b = 3 and ab = 4, what is a² + b²?
  33. 33.Find the value of x² − y² when x = 14 and y = 9.
  34. 34.Find the value of x² − y² when x = 5 and y = 4.
  35. 35.Use (a − b)² = a² − 2ab + b² to find 86².
  36. 36.Use (a − b)² = a² − 2ab + b² to find 44².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 79².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 56².
  39. 39.If a − b = 7 and ab = 30, what is a² + b²?
  40. 40.Use (a + b)² = a² + 2ab + b² to find 67².

Answer key

  1. 625
  2. 26
  3. 529
  4. 1521
  5. 68
  6. 2299
  7. 840
  8. 5
  9. 6084
  10. 7056
  11. 4624
  12. 676
  13. 6375
  14. 29
  15. 8649
  16. 1
  17. 10
  18. 5
  19. 40
  20. 1369
  21. 5624
  22. 4884
  23. 1849
  24. 336
  25. 10609
  26. 896
  27. 5307
  28. 7744
  29. 3072
  30. 36
  31. 61
  32. 17
  33. 115
  34. 9
  35. 7396
  36. 1936
  37. 6241
  38. 3136
  39. 109
  40. 4489

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