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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 340 · 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.Find the value of x² − 2xy + y² when x = 5 and y = 2.
  2. 2.Use (a + b)(a − b) = a² − b² to find 78 × 62.
  3. 3.Use a² − b² = (a + b)(a − b) to find 42² − 37².
  4. 4.If a − b = 3 and ab = 18, what is a² + b²?
  5. 5.If a + b = 11 and ab = 18, what is a² + b²?
  6. 6.Use (a − b)² = a² − 2ab + b² to find 95².
  7. 7.If a + b = 9 and ab = 14, what is a² + b²?
  8. 8.Use (a − b)² = a² − 2ab + b² to find 99².
  9. 9.Use (a − b)² = a² − 2ab + b² to find 31².
  10. 10.Use (a + b)² = a² + 2ab + b² to find 84².
  11. 11.Use a² − b² = (a + b)(a − b) to find 37² − 20².
  12. 12.Find the value of x² − 2xy + y² when x = 15 and y = 2.
  13. 13.Find the value of x² − 2xy + y² when x = 6 and y = 1.
  14. 14.If a − b = 2 and ab = 15, what is a² + b²?
  15. 15.Use (a + b)² = a² + 2ab + b² to find 104².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 75².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 73².
  18. 18.Find the value of x² + 2xy + y² when x = 12 and y = 11.
  19. 19.Use (a − b)² = a² − 2ab + b² to find 37².
  20. 20.Use a² − b² = (a + b)(a − b) to find 38² − 7².
  21. 21.Find the value of x² − y² when x = 6 and y = 1.
  22. 22.Use a² − b² = (a + b)(a − b) to find 45² − 44².
  23. 23.Use a² − b² = (a + b)(a − b) to find 82² − 36².
  24. 24.Use (a − b)² = a² − 2ab + b² to find 68².
  25. 25.Find the value of x² − 2xy + y² when x = 5 and y = 4.
  26. 26.Use (a + b)(a − b) = a² − b² to find 96 × 84.
  27. 27.Use (a + b)(a − b) = a² − b² to find 69 × 51.
  28. 28.Use (a − b)² = a² − 2ab + b² to find 64².
  29. 29.If a + b = 8 and ab = 7, what is a² + b²?
  30. 30.Use (a − b)² = a² − 2ab + b² to find 43².
  31. 31.Use (a + b)(a − b) = a² − b² to find 34 × 26.
  32. 32.Use (a + b)² = a² + 2ab + b² to find 107².
  33. 33.Find the value of x² − 2xy + y² when x = 10 and y = 8.
  34. 34.Find the value of x² + 2xy + y² when x = 8 and y = 3.
  35. 35.Use (a − b)² = a² − 2ab + b² to find 93².
  36. 36.If a + b = 13 and ab = 36, what is a² + b²?
  37. 37.Use a² − b² = (a + b)(a − b) to find 62² − 37².
  38. 38.Use (a + b)(a − b) = a² − b² to find 101 × 99.
  39. 39.Find the value of x² + 2xy + y² when x = 8 and y = 7.
  40. 40.Use (a + b)² = a² + 2ab + b² to find 16².

Answer key

  1. 9
  2. 4836
  3. 395
  4. 45
  5. 85
  6. 9025
  7. 53
  8. 9801
  9. 961
  10. 7056
  11. 969
  12. 169
  13. 25
  14. 34
  15. 10816
  16. 5625
  17. 5329
  18. 529
  19. 1369
  20. 1395
  21. 35
  22. 89
  23. 5428
  24. 4624
  25. 1
  26. 8064
  27. 3519
  28. 4096
  29. 50
  30. 1849
  31. 884
  32. 11449
  33. 4
  34. 121
  35. 8649
  36. 97
  37. 2475
  38. 9999
  39. 225
  40. 256

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