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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 282 · 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)(a − b) = a² − b² to find 73 × 67.
  2. 2.Use a² − b² = (a + b)(a − b) to find 64² − 25².
  3. 3.Use a² − b² = (a + b)(a − b) to find 81² − 5².
  4. 4.Use (a + b)(a − b) = a² − b² to find 25 × 15.
  5. 5.Use (a + b)² = a² + 2ab + b² to find 101².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 23².
  7. 7.If a + b = 14 and ab = 24, what is a² + b²?
  8. 8.Use (a − b)² = a² − 2ab + b² to find 59².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 29².
  10. 10.Find the value of x² + 2xy + y² when x = 6 and y = 5.
  11. 11.Find the value of x² + 2xy + y² when x = 14 and y = 1.
  12. 12.Use a² − b² = (a + b)(a − b) to find 64² − 34².
  13. 13.Find the value of x² + 2xy + y² when x = 11 and y = 6.
  14. 14.Use (a + b)(a − b) = a² − b² to find 28 × 12.
  15. 15.Use (a − b)² = a² − 2ab + b² to find 66².
  16. 16.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  17. 17.Use (a − b)² = a² − 2ab + b² to find 79².
  18. 18.If a + b = 8 and ab = 7, what is a² + b²?
  19. 19.Find the value of x² − y² when x = 14 and y = 11.
  20. 20.Use (a − b)² = a² − 2ab + b² to find 58².
  21. 21.Use a² − b² = (a + b)(a − b) to find 29² − 6².
  22. 22.Find the value of x² − 2xy + y² when x = 8 and y = 4.
  23. 23.If a + b = 5 and ab = 4, what is a² + b²?
  24. 24.Use a² − b² = (a + b)(a − b) to find 46² − 28².
  25. 25.Find the value of x² − y² when x = 5 and y = 3.
  26. 26.Use (a − b)² = a² − 2ab + b² to find 15².
  27. 27.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  28. 28.Find the value of x² + 2xy + y² when x = 10 and y = 8.
  29. 29.Use (a + b)² = a² + 2ab + b² to find 64².
  30. 30.Find the value of x² − 2xy + y² when x = 3 and y = 2.
  31. 31.Use (a + b)² = a² + 2ab + b² to find 85².
  32. 32.Use (a + b)² = a² + 2ab + b² to find 109².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 38².
  34. 34.Find the value of x² − 2xy + y² when x = 5 and y = 4.
  35. 35.Use a² − b² = (a + b)(a − b) to find 48² − 14².
  36. 36.Use (a + b)² = a² + 2ab + b² to find 25².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 53².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 47².
  39. 39.If a − b = 2 and ab = 120, what is a² + b²?
  40. 40.Use (a + b)(a − b) = a² − b² to find 102 × 98.

Answer key

  1. 4891
  2. 3471
  3. 6536
  4. 375
  5. 10201
  6. 529
  7. 148
  8. 3481
  9. 841
  10. 121
  11. 225
  12. 2940
  13. 289
  14. 336
  15. 4356
  16. 1591
  17. 6241
  18. 50
  19. 75
  20. 3364
  21. 805
  22. 16
  23. 17
  24. 1332
  25. 16
  26. 225
  27. 25
  28. 324
  29. 4096
  30. 1
  31. 7225
  32. 11881
  33. 1444
  34. 1
  35. 2108
  36. 625
  37. 2809
  38. 2209
  39. 244
  40. 9996

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