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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 571 · 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 96².
  2. 2.If a − b = 9 and ab = 22, what is a² + b²?
  3. 3.If a − b = 3 and ab = 4, what is a² + b²?
  4. 4.Use (a − b)² = a² − 2ab + b² to find 59².
  5. 5.Use (a + b)(a − b) = a² − b² to find 68 × 52.
  6. 6.Use (a + b)² = a² + 2ab + b² to find 22².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 65².
  8. 8.If a + b = 11 and ab = 18, what is a² + b²?
  9. 9.Use (a + b)(a − b) = a² − b² to find 66 × 54.
  10. 10.Use (a + b)² = a² + 2ab + b² to find 81².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 52².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 67².
  13. 13.Find the value of x² + 2xy + y² when x = 15 and y = 11.
  14. 14.Use (a − b)² = a² − 2ab + b² to find 12².
  15. 15.Use (a + b)(a − b) = a² − b² to find 88 × 72.
  16. 16.If a − b = 2 and ab = 15, what is a² + b²?
  17. 17.Use (a + b)² = a² + 2ab + b² to find 77².
  18. 18.Use (a + b)(a − b) = a² − b² to find 49 × 31.
  19. 19.Use (a + b)² = a² + 2ab + b² to find 46².
  20. 20.Find the value of x² + 2xy + y² when x = 9 and y = 2.
  21. 21.Use a² − b² = (a + b)(a − b) to find 27² − 8².
  22. 22.Find the value of x² − 2xy + y² when x = 4 and y = 1.
  23. 23.Use (a + b)² = a² + 2ab + b² to find 94².
  24. 24.Find the value of x² + 2xy + y² when x = 9 and y = 4.
  25. 25.Find the value of x² + 2xy + y² when x = 13 and y = 4.
  26. 26.Find the value of x² − 2xy + y² when x = 14 and y = 3.
  27. 27.If a − b = 2 and ab = 63, what is a² + b²?
  28. 28.Use a² − b² = (a + b)(a − b) to find 28² − 5².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 64².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 21².
  31. 31.If a + b = 9 and ab = 20, what is a² + b²?
  32. 32.Use (a + b)² = a² + 2ab + b² to find 14².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 34².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 69².
  35. 35.Find the value of x² + 2xy + y² when x = 8 and y = 7.
  36. 36.Use a² − b² = (a + b)(a − b) to find 95² − 26².
  37. 37.Use (a + b)² = a² + 2ab + b² to find 44².
  38. 38.Use a² − b² = (a + b)(a − b) to find 36² − 7².
  39. 39.If a − b = 3 and ab = 70, what is a² + b²?
  40. 40.Use (a + b)² = a² + 2ab + b² to find 19².

Answer key

  1. 9216
  2. 125
  3. 17
  4. 3481
  5. 3536
  6. 484
  7. 4225
  8. 85
  9. 3564
  10. 6561
  11. 2704
  12. 4489
  13. 676
  14. 144
  15. 6336
  16. 34
  17. 5929
  18. 1519
  19. 2116
  20. 121
  21. 665
  22. 9
  23. 8836
  24. 169
  25. 289
  26. 121
  27. 130
  28. 759
  29. 4096
  30. 441
  31. 41
  32. 196
  33. 1156
  34. 4761
  35. 225
  36. 8349
  37. 1936
  38. 1247
  39. 149
  40. 361

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