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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 542 · 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 15².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 51².
  3. 3.Use (a + b)(a − b) = a² − b² to find 48 × 32.
  4. 4.Use a² − b² = (a + b)(a − b) to find 29² − 24².
  5. 5.Use a² − b² = (a + b)(a − b) to find 53² − 43².
  6. 6.Use (a + b)² = a² + 2ab + b² to find 53².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 86².
  8. 8.If a + b = 11 and ab = 24, what is a² + b²?
  9. 9.Use (a + b)(a − b) = a² − b² to find 88 × 72.
  10. 10.Use (a − b)² = a² − 2ab + b² to find 12².
  11. 11.Use a² − b² = (a + b)(a − b) to find 26² − 25².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 13².
  13. 13.Find the value of x² − 2xy + y² when x = 3 and y = 2.
  14. 14.Find the value of x² + 2xy + y² when x = 4 and y = 2.
  15. 15.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  16. 16.Use (a − b)² = a² − 2ab + b² to find 14².
  17. 17.Find the value of x² − y² when x = 3 and y = 1.
  18. 18.Use a² − b² = (a + b)(a − b) to find 71² − 48².
  19. 19.Use (a − b)² = a² − 2ab + b² to find 39².
  20. 20.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  21. 21.Use (a − b)² = a² − 2ab + b² to find 46².
  22. 22.Use (a − b)² = a² − 2ab + b² to find 99².
  23. 23.Use (a + b)(a − b) = a² − b² to find 81 × 79.
  24. 24.Find the value of x² − 2xy + y² when x = 6 and y = 4.
  25. 25.If a + b = 13 and ab = 22, what is a² + b²?
  26. 26.Find the value of x² + 2xy + y² when x = 14 and y = 1.
  27. 27.Use a² − b² = (a + b)(a − b) to find 96² − 73².
  28. 28.If a − b = 3 and ab = 10, what is a² + b²?
  29. 29.Find the value of x² + 2xy + y² when x = 4 and y = 3.
  30. 30.Use (a + b)² = a² + 2ab + b² to find 76².
  31. 31.Find the value of x² − 2xy + y² when x = 12 and y = 1.
  32. 32.Use (a − b)² = a² − 2ab + b² to find 35².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 32².
  34. 34.Find the value of x² − 2xy + y² when x = 3 and y = 1.
  35. 35.Use (a − b)² = a² − 2ab + b² to find 49².
  36. 36.Use (a + b)² = a² + 2ab + b² to find 109².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 69².
  38. 38.Find the value of x² − 2xy + y² when x = 11 and y = 7.
  39. 39.Find the value of x² + 2xy + y² when x = 15 and y = 11.
  40. 40.Use (a + b)(a − b) = a² − b² to find 79 × 61.

Answer key

  1. 225
  2. 2601
  3. 1536
  4. 265
  5. 960
  6. 2809
  7. 7396
  8. 73
  9. 6336
  10. 144
  11. 51
  12. 169
  13. 1
  14. 36
  15. 875
  16. 196
  17. 8
  18. 2737
  19. 1521
  20. 25
  21. 2116
  22. 9801
  23. 6399
  24. 4
  25. 125
  26. 225
  27. 3887
  28. 29
  29. 49
  30. 5776
  31. 121
  32. 1225
  33. 1024
  34. 4
  35. 2401
  36. 11881
  37. 4761
  38. 16
  39. 676
  40. 4819

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