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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 610 · 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 107 × 93.
  2. 2.Use (a + b)(a − b) = a² − b² to find 64 × 56.
  3. 3.Use (a + b)² = a² + 2ab + b² to find 66².
  4. 4.If a − b = 2 and ab = 3, what is a² + b²?
  5. 5.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  6. 6.Find the value of x² − y² when x = 7 and y = 1.
  7. 7.Use (a + b)² = a² + 2ab + b² to find 21².
  8. 8.If a + b = 15 and ab = 50, what is a² + b²?
  9. 9.Find the value of x² − 2xy + y² when x = 5 and y = 3.
  10. 10.Use (a + b)² = a² + 2ab + b² to find 57².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 19².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 16².
  13. 13.Use (a + b)² = a² + 2ab + b² to find 93².
  14. 14.If a − b = 6 and ab = 55, what is a² + b²?
  15. 15.Find the value of x² − 2xy + y² when x = 5 and y = 1.
  16. 16.Use a² − b² = (a + b)(a − b) to find 57² − 51².
  17. 17.Find the value of x² + 2xy + y² when x = 13 and y = 12.
  18. 18.Use a² − b² = (a + b)(a − b) to find 83² − 43².
  19. 19.Use (a + b)(a − b) = a² − b² to find 95 × 85.
  20. 20.Find the value of x² − 2xy + y² when x = 13 and y = 1.
  21. 21.Find the value of x² − 2xy + y² when x = 13 and y = 4.
  22. 22.Use (a − b)² = a² − 2ab + b² to find 32².
  23. 23.Use (a − b)² = a² − 2ab + b² to find 66².
  24. 24.Use a² − b² = (a + b)(a − b) to find 39² − 12².
  25. 25.Use (a + b)² = a² + 2ab + b² to find 25².
  26. 26.Use a² − b² = (a + b)(a − b) to find 25² − 19².
  27. 27.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  28. 28.Use a² − b² = (a + b)(a − b) to find 26² − 1².
  29. 29.Use (a − b)² = a² − 2ab + b² to find 52².
  30. 30.Use (a + b)(a − b) = a² − b² to find 94 × 86.
  31. 31.Use (a − b)² = a² − 2ab + b² to find 21².
  32. 32.Use a² − b² = (a + b)(a − b) to find 62² − 12².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 65².
  34. 34.Use a² − b² = (a + b)(a − b) to find 26² − 23².
  35. 35.Use (a + b)² = a² + 2ab + b² to find 83².
  36. 36.If a + b = 7 and ab = 12, what is a² + b²?
  37. 37.Find the value of x² − y² when x = 15 and y = 9.
  38. 38.Use a² − b² = (a + b)(a − b) to find 51² − 20².
  39. 39.Use (a + b)(a − b) = a² − b² to find 24 × 16.
  40. 40.Find the value of x² − y² when x = 10 and y = 3.

Answer key

  1. 9951
  2. 3584
  3. 4356
  4. 10
  5. 899
  6. 48
  7. 441
  8. 125
  9. 4
  10. 3249
  11. 361
  12. 256
  13. 8649
  14. 146
  15. 16
  16. 648
  17. 625
  18. 5040
  19. 8075
  20. 144
  21. 81
  22. 1024
  23. 4356
  24. 1377
  25. 625
  26. 264
  27. 25
  28. 675
  29. 2704
  30. 8084
  31. 441
  32. 3700
  33. 4225
  34. 147
  35. 6889
  36. 25
  37. 144
  38. 2201
  39. 384
  40. 91

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