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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 359 · 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 15².
  2. 2.If a − b = 1 and ab = 6, what is a² + b²?
  3. 3.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  4. 4.Use (a − b)² = a² − 2ab + b² to find 79².
  5. 5.Find the value of x² − 2xy + y² when x = 4 and y = 1.
  6. 6.Use (a + b)² = a² + 2ab + b² to find 63².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 33².
  8. 8.Use (a + b)² = a² + 2ab + b² to find 29².
  9. 9.Find the value of x² − y² when x = 12 and y = 7.
  10. 10.Use (a − b)² = a² − 2ab + b² to find 65².
  11. 11.Find the value of x² − y² when x = 8 and y = 1.
  12. 12.Use (a + b)² = a² + 2ab + b² to find 13².
  13. 13.Use a² − b² = (a + b)(a − b) to find 63² − 6².
  14. 14.Use (a − b)² = a² − 2ab + b² to find 61².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 47².
  16. 16.If a − b = 8 and ab = 9, what is a² + b²?
  17. 17.Find the value of x² − y² when x = 14 and y = 6.
  18. 18.Use a² − b² = (a + b)(a − b) to find 57² − 5².
  19. 19.Use a² − b² = (a + b)(a − b) to find 80² − 69².
  20. 20.If a + b = 3 and ab = 2, what is a² + b²?
  21. 21.Use (a + b)(a − b) = a² − b² to find 24 × 16.
  22. 22.Use (a + b)² = a² + 2ab + b² to find 75².
  23. 23.Find the value of x² + 2xy + y² when x = 8 and y = 1.
  24. 24.Use (a + b)² = a² + 2ab + b² to find 26².
  25. 25.Use (a + b)² = a² + 2ab + b² to find 25².
  26. 26.Use (a − b)² = a² − 2ab + b² to find 26².
  27. 27.Use (a − b)² = a² − 2ab + b² to find 92².
  28. 28.If a + b = 14 and ab = 48, what is a² + b²?
  29. 29.Use (a + b)² = a² + 2ab + b² to find 47².
  30. 30.Use a² − b² = (a + b)(a − b) to find 43² − 10².
  31. 31.Use (a − b)² = a² − 2ab + b² to find 17².
  32. 32.Use (a − b)² = a² − 2ab + b² to find 31².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 87².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 86².
  35. 35.Use (a + b)(a − b) = a² − b² to find 34 × 26.
  36. 36.Use (a − b)² = a² − 2ab + b² to find 87².
  37. 37.Find the value of x² − 2xy + y² when x = 5 and y = 3.
  38. 38.If a + b = 20 and ab = 96, what is a² + b²?
  39. 39.Use (a + b)(a − b) = a² − b² to find 27 × 13.
  40. 40.Use (a + b)(a − b) = a² − b² to find 95 × 85.

Answer key

  1. 225
  2. 13
  3. 25
  4. 6241
  5. 9
  6. 3969
  7. 1089
  8. 841
  9. 95
  10. 4225
  11. 63
  12. 169
  13. 3933
  14. 3721
  15. 2209
  16. 82
  17. 160
  18. 3224
  19. 1639
  20. 5
  21. 384
  22. 5625
  23. 81
  24. 676
  25. 625
  26. 676
  27. 8464
  28. 100
  29. 2209
  30. 1749
  31. 289
  32. 961
  33. 7569
  34. 7396
  35. 884
  36. 7569
  37. 4
  38. 208
  39. 351
  40. 8075

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