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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 226 · 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 49 × 31.
  2. 2.Use (a + b)(a − b) = a² − b² to find 75 × 65.
  3. 3.If a − b = 2 and ab = 3, what is a² + b²?
  4. 4.Use (a + b)(a − b) = a² − b² to find 61 × 59.
  5. 5.If a − b = 10 and ab = 11, what is a² + b²?
  6. 6.Use (a + b)(a − b) = a² − b² to find 37 × 23.
  7. 7.If a + b = 12 and ab = 27, what is a² + b²?
  8. 8.Use a² − b² = (a + b)(a − b) to find 61² − 22².
  9. 9.Use (a − b)² = a² − 2ab + b² to find 93².
  10. 10.Use (a + b)(a − b) = a² − b² to find 55 × 45.
  11. 11.Use (a − b)² = a² − 2ab + b² to find 52².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 75².
  13. 13.Use (a + b)(a − b) = a² − b² to find 41 × 39.
  14. 14.Use (a + b)² = a² + 2ab + b² to find 101².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 23².
  16. 16.Find the value of x² − y² when x = 5 and y = 1.
  17. 17.Use (a + b)² = a² + 2ab + b² to find 26².
  18. 18.Use a² − b² = (a + b)(a − b) to find 81² − 63².
  19. 19.Use (a − b)² = a² − 2ab + b² to find 25².
  20. 20.Use (a + b)² = a² + 2ab + b² to find 86².
  21. 21.Use a² − b² = (a + b)(a − b) to find 76² − 53².
  22. 22.Find the value of x² − 2xy + y² when x = 9 and y = 1.
  23. 23.Use (a + b)(a − b) = a² − b² to find 38 × 22.
  24. 24.Use a² − b² = (a + b)(a − b) to find 40² − 21².
  25. 25.Use (a + b)(a − b) = a² − b² to find 47 × 33.
  26. 26.If a − b = 1 and ab = 6, what is a² + b²?
  27. 27.Use (a + b)² = a² + 2ab + b² to find 92².
  28. 28.Find the value of x² − 2xy + y² when x = 6 and y = 2.
  29. 29.Use (a + b)² = a² + 2ab + b² to find 24².
  30. 30.Use (a + b)(a − b) = a² − b² to find 64 × 56.
  31. 31.Use a² − b² = (a + b)(a − b) to find 55² − 34².
  32. 32.If a + b = 17 and ab = 60, what is a² + b²?
  33. 33.Use a² − b² = (a + b)(a − b) to find 62² − 7².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 69².
  35. 35.Use a² − b² = (a + b)(a − b) to find 35² − 17².
  36. 36.Find the value of x² − 2xy + y² when x = 14 and y = 6.
  37. 37.Use a² − b² = (a + b)(a − b) to find 28² − 25².
  38. 38.Use (a + b)(a − b) = a² − b² to find 83 × 77.
  39. 39.If a − b = 3 and ab = 40, what is a² + b²?
  40. 40.Use a² − b² = (a + b)(a − b) to find 67² − 2².

Answer key

  1. 1519
  2. 4875
  3. 10
  4. 3599
  5. 122
  6. 851
  7. 90
  8. 3237
  9. 8649
  10. 2475
  11. 2704
  12. 5625
  13. 1599
  14. 10201
  15. 529
  16. 24
  17. 676
  18. 2592
  19. 625
  20. 7396
  21. 2967
  22. 64
  23. 836
  24. 1159
  25. 1551
  26. 13
  27. 8464
  28. 16
  29. 576
  30. 3584
  31. 1869
  32. 169
  33. 3795
  34. 4761
  35. 936
  36. 64
  37. 159
  38. 6391
  39. 89
  40. 4485

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