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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 375 · 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 27².
  2. 2.Use (a + b)(a − b) = a² − b² to find 64 × 56.
  3. 3.Find the value of x² − y² when x = 7 and y = 2.
  4. 4.Use a² − b² = (a + b)(a − b) to find 76² − 52².
  5. 5.Find the value of x² + 2xy + y² when x = 12 and y = 6.
  6. 6.Use (a + b)² = a² + 2ab + b² to find 23².
  7. 7.Find the value of x² + 2xy + y² when x = 10 and y = 5.
  8. 8.Use a² − b² = (a + b)(a − b) to find 53² − 29².
  9. 9.If a + b = 21 and ab = 108, what is a² + b²?
  10. 10.Use (a − b)² = a² − 2ab + b² to find 69².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 45².
  12. 12.If a − b = 2 and ab = 15, what is a² + b²?
  13. 13.Use (a − b)² = a² − 2ab + b² to find 37².
  14. 14.Use (a + b)² = a² + 2ab + b² to find 42².
  15. 15.If a − b = 3 and ab = 4, what is a² + b²?
  16. 16.Use (a + b)² = a² + 2ab + b² to find 14².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 47².
  18. 18.Use (a + b)² = a² + 2ab + b² to find 94².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 82².
  20. 20.Find the value of x² − y² when x = 11 and y = 10.
  21. 21.Use (a − b)² = a² − 2ab + b² to find 82².
  22. 22.Use (a − b)² = a² − 2ab + b² to find 11².
  23. 23.Use (a + b)² = a² + 2ab + b² to find 17².
  24. 24.Find the value of x² − y² when x = 15 and y = 3.
  25. 25.Use (a − b)² = a² − 2ab + b² to find 15².
  26. 26.Use (a + b)(a − b) = a² − b² to find 46 × 34.
  27. 27.Find the value of x² + 2xy + y² when x = 6 and y = 3.
  28. 28.If a − b = 7 and ab = 8, what is a² + b²?
  29. 29.Use (a + b)² = a² + 2ab + b² to find 29².
  30. 30.Use (a − b)² = a² − 2ab + b² to find 78².
  31. 31.Use (a + b)(a − b) = a² − b² to find 55 × 45.
  32. 32.Use (a − b)² = a² − 2ab + b² to find 33².
  33. 33.If a − b = 3 and ab = 10, what is a² + b²?
  34. 34.If a + b = 15 and ab = 54, what is a² + b²?
  35. 35.If a + b = 4 and ab = 3, what is a² + b²?
  36. 36.Use (a + b)² = a² + 2ab + b² to find 75².
  37. 37.If a − b = 1 and ab = 132, what is a² + b²?
  38. 38.Use (a + b)² = a² + 2ab + b² to find 103².
  39. 39.Use (a − b)² = a² − 2ab + b² to find 75².
  40. 40.If a + b = 11 and ab = 10, what is a² + b²?

Answer key

  1. 729
  2. 3584
  3. 45
  4. 3072
  5. 324
  6. 529
  7. 225
  8. 1968
  9. 225
  10. 4761
  11. 2025
  12. 34
  13. 1369
  14. 1764
  15. 17
  16. 196
  17. 2209
  18. 8836
  19. 6724
  20. 21
  21. 6724
  22. 121
  23. 289
  24. 216
  25. 225
  26. 1564
  27. 81
  28. 65
  29. 841
  30. 6084
  31. 2475
  32. 1089
  33. 29
  34. 117
  35. 10
  36. 5625
  37. 265
  38. 10609
  39. 5625
  40. 101

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