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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 93 · 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 25².
  2. 2.Use a² − b² = (a + b)(a − b) to find 32² − 21².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 11².
  4. 4.Find the value of x² − 2xy + y² when x = 12 and y = 9.
  5. 5.If a − b = 1 and ab = 12, what is a² + b²?
  6. 6.If a + b = 12 and ab = 35, what is a² + b²?
  7. 7.Use (a − b)² = a² − 2ab + b² to find 18².
  8. 8.Use (a + b)² = a² + 2ab + b² to find 74².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 53².
  10. 10.If a + b = 11 and ab = 18, what is a² + b²?
  11. 11.Use (a − b)² = a² − 2ab + b² to find 21².
  12. 12.If a − b = 1 and ab = 2, what is a² + b²?
  13. 13.Find the value of x² + 2xy + y² when x = 12 and y = 5.
  14. 14.Use (a + b)² = a² + 2ab + b² to find 56².
  15. 15.Use (a + b)² = a² + 2ab + b² to find 39².
  16. 16.Use (a − b)² = a² − 2ab + b² to find 19².
  17. 17.Find the value of x² − y² when x = 12 and y = 7.
  18. 18.If a − b = 2 and ab = 3, what is a² + b²?
  19. 19.Find the value of x² − 2xy + y² when x = 11 and y = 7.
  20. 20.Use (a − b)² = a² − 2ab + b² to find 38².
  21. 21.If a − b = 1 and ab = 20, what is a² + b²?
  22. 22.Use (a − b)² = a² − 2ab + b² to find 98².
  23. 23.Use (a + b)(a − b) = a² − b² to find 53 × 47.
  24. 24.If a + b = 5 and ab = 4, what is a² + b²?
  25. 25.Use (a − b)² = a² − 2ab + b² to find 74².
  26. 26.Use a² − b² = (a + b)(a − b) to find 42² − 11².
  27. 27.Use (a + b)² = a² + 2ab + b² to find 16².
  28. 28.If a + b = 15 and ab = 44, what is a² + b²?
  29. 29.Use a² − b² = (a + b)(a − b) to find 38² − 31².
  30. 30.Use a² − b² = (a + b)(a − b) to find 37² − 28².
  31. 31.If a + b = 6 and ab = 5, what is a² + b²?
  32. 32.Find the value of x² − y² when x = 4 and y = 2.
  33. 33.Use (a − b)² = a² − 2ab + b² to find 15².
  34. 34.Use (a + b)(a − b) = a² − b² to find 63 × 57.
  35. 35.If a − b = 5 and ab = 36, what is a² + b²?
  36. 36.Find the value of x² − 2xy + y² when x = 11 and y = 1.
  37. 37.Use a² − b² = (a + b)(a − b) to find 33² − 12².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 76².
  39. 39.Use (a − b)² = a² − 2ab + b² to find 71².
  40. 40.Use (a − b)² = a² − 2ab + b² to find 73².

Answer key

  1. 625
  2. 583
  3. 121
  4. 9
  5. 25
  6. 74
  7. 324
  8. 5476
  9. 2809
  10. 85
  11. 441
  12. 5
  13. 289
  14. 3136
  15. 1521
  16. 361
  17. 95
  18. 10
  19. 16
  20. 1444
  21. 41
  22. 9604
  23. 2491
  24. 17
  25. 5476
  26. 1643
  27. 256
  28. 137
  29. 483
  30. 585
  31. 26
  32. 12
  33. 225
  34. 3591
  35. 97
  36. 100
  37. 945
  38. 5776
  39. 5041
  40. 5329

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