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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 432 · 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 92².
  2. 2.If a + b = 3 and ab = 2, what is a² + b²?
  3. 3.Use a² − b² = (a + b)(a − b) to find 96² − 24².
  4. 4.Find the value of x² − y² when x = 9 and y = 5.
  5. 5.Use (a + b)(a − b) = a² − b² to find 74 × 66.
  6. 6.If a + b = 5 and ab = 6, what is a² + b²?
  7. 7.Find the value of x² − 2xy + y² when x = 4 and y = 3.
  8. 8.Find the value of x² − y² when x = 10 and y = 1.
  9. 9.Use (a − b)² = a² − 2ab + b² to find 73².
  10. 10.Use (a + b)² = a² + 2ab + b² to find 84².
  11. 11.Find the value of x² + 2xy + y² when x = 6 and y = 5.
  12. 12.Use (a − b)² = a² − 2ab + b² to find 64².
  13. 13.Use (a + b)² = a² + 2ab + b² to find 59².
  14. 14.Use (a + b)² = a² + 2ab + b² to find 85².
  15. 15.Use (a + b)² = a² + 2ab + b² to find 108².
  16. 16.Use (a − b)² = a² − 2ab + b² to find 83².
  17. 17.Use (a + b)(a − b) = a² − b² to find 69 × 51.
  18. 18.Use (a + b)(a − b) = a² − b² to find 51 × 49.
  19. 19.Find the value of x² + 2xy + y² when x = 11 and y = 6.
  20. 20.Use a² − b² = (a + b)(a − b) to find 43² − 32².
  21. 21.Use (a − b)² = a² − 2ab + b² to find 97².
  22. 22.Use (a − b)² = a² − 2ab + b² to find 32².
  23. 23.Use (a − b)² = a² − 2ab + b² to find 24².
  24. 24.Use a² − b² = (a + b)(a − b) to find 45² − 15².
  25. 25.Use (a + b)(a − b) = a² − b² to find 53 × 47.
  26. 26.Use a² − b² = (a + b)(a − b) to find 33² − 8².
  27. 27.Use (a + b)(a − b) = a² − b² to find 103 × 97.
  28. 28.Find the value of x² − y² when x = 12 and y = 5.
  29. 29.Use (a − b)² = a² − 2ab + b² to find 53².
  30. 30.If a + b = 12 and ab = 20, what is a² + b²?
  31. 31.Use a² − b² = (a + b)(a − b) to find 58² − 20².
  32. 32.Use (a − b)² = a² − 2ab + b² to find 88².
  33. 33.Use (a − b)² = a² − 2ab + b² to find 19².
  34. 34.Find the value of x² + 2xy + y² when x = 4 and y = 3.
  35. 35.If a − b = 3 and ab = 28, what is a² + b²?
  36. 36.Use (a + b)(a − b) = a² − b² to find 102 × 98.
  37. 37.Use (a + b)² = a² + 2ab + b² to find 103².
  38. 38.Use a² − b² = (a + b)(a − b) to find 26² − 21².
  39. 39.Use a² − b² = (a + b)(a − b) to find 77² − 8².
  40. 40.If a − b = 2 and ab = 3, what is a² + b²?

Answer key

  1. 8464
  2. 5
  3. 8640
  4. 56
  5. 4884
  6. 13
  7. 1
  8. 99
  9. 5329
  10. 7056
  11. 121
  12. 4096
  13. 3481
  14. 7225
  15. 11664
  16. 6889
  17. 3519
  18. 2499
  19. 289
  20. 825
  21. 9409
  22. 1024
  23. 576
  24. 1800
  25. 2491
  26. 1025
  27. 9991
  28. 119
  29. 2809
  30. 104
  31. 2964
  32. 7744
  33. 361
  34. 49
  35. 65
  36. 9996
  37. 10609
  38. 235
  39. 5865
  40. 10

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