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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 214 · 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 66² − 38².
  2. 2.Use a² − b² = (a + b)(a − b) to find 32² − 9².
  3. 3.Use (a + b)² = a² + 2ab + b² to find 34².
  4. 4.Use (a + b)(a − b) = a² − b² to find 106 × 94.
  5. 5.Find the value of x² − 2xy + y² when x = 7 and y = 4.
  6. 6.Use (a + b)² = a² + 2ab + b² to find 63².
  7. 7.Use a² − b² = (a + b)(a − b) to find 58² − 18².
  8. 8.Use (a + b)(a − b) = a² − b² to find 67 × 53.
  9. 9.Use (a + b)² = a² + 2ab + b² to find 42².
  10. 10.If a − b = 6 and ab = 72, what is a² + b²?
  11. 11.Use (a − b)² = a² − 2ab + b² to find 89².
  12. 12.Use a² − b² = (a + b)(a − b) to find 22² − 3².
  13. 13.If a − b = 4 and ab = 32, what is a² + b²?
  14. 14.Use a² − b² = (a + b)(a − b) to find 30² − 29².
  15. 15.If a − b = 3 and ab = 4, what is a² + b²?
  16. 16.Use (a + b)² = a² + 2ab + b² to find 58².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 87².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 75².
  19. 19.Use (a − b)² = a² − 2ab + b² to find 83².
  20. 20.Use a² − b² = (a + b)(a − b) to find 38² − 10².
  21. 21.Use a² − b² = (a + b)(a − b) to find 69² − 64².
  22. 22.Use (a + b)² = a² + 2ab + b² to find 38².
  23. 23.Use (a + b)(a − b) = a² − b² to find 109 × 91.
  24. 24.Use (a − b)² = a² − 2ab + b² to find 71².
  25. 25.Find the value of x² − y² when x = 7 and y = 5.
  26. 26.Use (a + b)² = a² + 2ab + b² to find 35².
  27. 27.If a − b = 8 and ab = 48, what is a² + b²?
  28. 28.If a − b = 1 and ab = 110, what is a² + b²?
  29. 29.Use (a + b)² = a² + 2ab + b² to find 47².
  30. 30.Use (a + b)(a − b) = a² − b² to find 27 × 13.
  31. 31.Use (a − b)² = a² − 2ab + b² to find 55².
  32. 32.If a − b = 2 and ab = 24, what is a² + b²?
  33. 33.Use (a − b)² = a² − 2ab + b² to find 38².
  34. 34.Use (a − b)² = a² − 2ab + b² to find 68².
  35. 35.Use a² − b² = (a + b)(a − b) to find 32² − 11².
  36. 36.Use (a + b)(a − b) = a² − b² to find 64 × 56.
  37. 37.Use (a + b)² = a² + 2ab + b² to find 85².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 37².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 21².
  40. 40.Use (a + b)² = a² + 2ab + b² to find 86².

Answer key

  1. 2912
  2. 943
  3. 1156
  4. 9964
  5. 9
  6. 3969
  7. 3040
  8. 3551
  9. 1764
  10. 180
  11. 7921
  12. 475
  13. 80
  14. 59
  15. 17
  16. 3364
  17. 7569
  18. 5625
  19. 6889
  20. 1344
  21. 665
  22. 1444
  23. 9919
  24. 5041
  25. 24
  26. 1225
  27. 160
  28. 221
  29. 2209
  30. 351
  31. 3025
  32. 52
  33. 1444
  34. 4624
  35. 903
  36. 3584
  37. 7225
  38. 1369
  39. 441
  40. 7396

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