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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 745 · 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 35².
  2. 2.Use (a − b)² = a² − 2ab + b² to find 41².
  3. 3.Use (a + b)² = a² + 2ab + b² to find 13².
  4. 4.Use (a − b)² = a² − 2ab + b² to find 71².
  5. 5.Use (a − b)² = a² − 2ab + b² to find 21².
  6. 6.If a − b = 9 and ab = 36, what is a² + b²?
  7. 7.Use (a + b)² = a² + 2ab + b² to find 17².
  8. 8.If a + b = 6 and ab = 8, what is a² + b²?
  9. 9.Use a² − b² = (a + b)(a − b) to find 86² − 65².
  10. 10.Find the value of x² − y² when x = 10 and y = 8.
  11. 11.Use (a + b)² = a² + 2ab + b² to find 103².
  12. 12.Find the value of x² + 2xy + y² when x = 8 and y = 6.
  13. 13.Find the value of x² + 2xy + y² when x = 13 and y = 9.
  14. 14.Use (a + b)(a − b) = a² − b² to find 41 × 39.
  15. 15.If a − b = 4 and ab = 21, what is a² + b²?
  16. 16.Use a² − b² = (a + b)(a − b) to find 79² − 52².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 66².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 88².
  19. 19.Use (a + b)(a − b) = a² − b² to find 82 × 78.
  20. 20.Use (a + b)² = a² + 2ab + b² to find 61².
  21. 21.Use (a − b)² = a² − 2ab + b² to find 77².
  22. 22.Use (a + b)² = a² + 2ab + b² to find 96².
  23. 23.Use a² − b² = (a + b)(a − b) to find 36² − 7².
  24. 24.Use (a + b)(a − b) = a² − b² to find 69 × 51.
  25. 25.Use (a − b)² = a² − 2ab + b² to find 34².
  26. 26.Use a² − b² = (a + b)(a − b) to find 87² − 26².
  27. 27.Use (a − b)² = a² − 2ab + b² to find 57².
  28. 28.If a − b = 7 and ab = 44, what is a² + b²?
  29. 29.Find the value of x² − 2xy + y² when x = 13 and y = 9.
  30. 30.Use a² − b² = (a + b)(a − b) to find 72² − 9².
  31. 31.Use (a + b)(a − b) = a² − b² to find 26 × 14.
  32. 32.Use (a + b)² = a² + 2ab + b² to find 109².
  33. 33.Find the value of x² + 2xy + y² when x = 11 and y = 6.
  34. 34.If a − b = 4 and ab = 32, what is a² + b²?
  35. 35.Use (a + b)² = a² + 2ab + b² to find 27².
  36. 36.Use (a − b)² = a² − 2ab + b² to find 94².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 17².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 47².
  39. 39.Use a² − b² = (a + b)(a − b) to find 32² − 2².
  40. 40.Use (a + b)² = a² + 2ab + b² to find 12².

Answer key

  1. 1225
  2. 1681
  3. 169
  4. 5041
  5. 441
  6. 153
  7. 289
  8. 20
  9. 3171
  10. 36
  11. 10609
  12. 196
  13. 484
  14. 1599
  15. 58
  16. 3537
  17. 4356
  18. 7744
  19. 6396
  20. 3721
  21. 5929
  22. 9216
  23. 1247
  24. 3519
  25. 1156
  26. 6893
  27. 3249
  28. 137
  29. 16
  30. 5103
  31. 364
  32. 11881
  33. 289
  34. 80
  35. 729
  36. 8836
  37. 289
  38. 2209
  39. 1020
  40. 144

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