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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 192 · 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 a² − b² = (a + b)(a − b) to find 45² − 26².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 64².
  3. 3.If a − b = 8 and ab = 48, what is a² + b²?
  4. 4.Use a² − b² = (a + b)(a − b) to find 92² − 22².
  5. 5.Use (a − b)² = a² − 2ab + b² to find 62².
  6. 6.Use (a + b)² = a² + 2ab + b² to find 104².
  7. 7.Use (a + b)(a − b) = a² − b² to find 75 × 65.
  8. 8.Find the value of x² − 2xy + y² when x = 11 and y = 10.
  9. 9.Use (a + b)² = a² + 2ab + b² to find 31².
  10. 10.If a − b = 1 and ab = 72, what is a² + b²?
  11. 11.Use (a − b)² = a² − 2ab + b² to find 19².
  12. 12.Use (a + b)(a − b) = a² − b² to find 63 × 57.
  13. 13.Use (a + b)² = a² + 2ab + b² to find 106².
  14. 14.Find the value of x² + 2xy + y² when x = 3 and y = 1.
  15. 15.Use (a − b)² = a² − 2ab + b² to find 31².
  16. 16.Use (a − b)² = a² − 2ab + b² to find 66².
  17. 17.Use (a + b)(a − b) = a² − b² to find 22 × 18.
  18. 18.Use (a + b)(a − b) = a² − b² to find 27 × 13.
  19. 19.Use (a + b)² = a² + 2ab + b² to find 18².
  20. 20.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  21. 21.Use (a + b)(a − b) = a² − b² to find 61 × 59.
  22. 22.Find the value of x² + 2xy + y² when x = 11 and y = 8.
  23. 23.Use a² − b² = (a + b)(a − b) to find 93² − 8².
  24. 24.Use (a − b)² = a² − 2ab + b² to find 42².
  25. 25.Use a² − b² = (a + b)(a − b) to find 55² − 49².
  26. 26.Find the value of x² + 2xy + y² when x = 13 and y = 10.
  27. 27.Use (a − b)² = a² − 2ab + b² to find 32².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 58².
  29. 29.Use a² − b² = (a + b)(a − b) to find 26² − 22².
  30. 30.If a − b = 3 and ab = 108, what is a² + b²?
  31. 31.Use (a + b)(a − b) = a² − b² to find 98 × 82.
  32. 32.Use (a − b)² = a² − 2ab + b² to find 25².
  33. 33.If a + b = 7 and ab = 12, what is a² + b²?
  34. 34.If a + b = 5 and ab = 6, what is a² + b²?
  35. 35.Use (a + b)² = a² + 2ab + b² to find 102².
  36. 36.Use (a − b)² = a² − 2ab + b² to find 91².
  37. 37.Use (a + b)² = a² + 2ab + b² to find 24².
  38. 38.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  39. 39.Use a² − b² = (a + b)(a − b) to find 26² − 3².
  40. 40.Use a² − b² = (a + b)(a − b) to find 84² − 21².

Answer key

  1. 1349
  2. 4096
  3. 160
  4. 7980
  5. 3844
  6. 10816
  7. 4875
  8. 1
  9. 961
  10. 145
  11. 361
  12. 3591
  13. 11236
  14. 16
  15. 961
  16. 4356
  17. 396
  18. 351
  19. 324
  20. 899
  21. 3599
  22. 361
  23. 8585
  24. 1764
  25. 624
  26. 529
  27. 1024
  28. 3364
  29. 192
  30. 225
  31. 8036
  32. 625
  33. 25
  34. 13
  35. 10404
  36. 8281
  37. 576
  38. 1591
  39. 667
  40. 6615

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