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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 627 · 40 sums
TalentJR

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 22².
  2. 2.If a − b = 4 and ab = 5, what is a² + b²?
  3. 3.Use (a + b)² = a² + 2ab + b² to find 68².
  4. 4.Use (a + b)² = a² + 2ab + b² to find 64².
  5. 5.Find the value of x² − 2xy + y² when x = 7 and y = 2.
  6. 6.Use (a + b)² = a² + 2ab + b² to find 37².
  7. 7.Use a² − b² = (a + b)(a − b) to find 50² − 5².
  8. 8.Use (a + b)² = a² + 2ab + b² to find 32².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 31².
  10. 10.If a + b = 5 and ab = 4, what is a² + b²?
  11. 11.Use (a + b)² = a² + 2ab + b² to find 24².
  12. 12.Find the value of x² − y² when x = 15 and y = 14.
  13. 13.If a − b = 1 and ab = 6, what is a² + b²?
  14. 14.If a − b = 2 and ab = 3, what is a² + b²?
  15. 15.Use (a + b)(a − b) = a² − b² to find 27 × 13.
  16. 16.Use (a + b)² = a² + 2ab + b² to find 88².
  17. 17.Find the value of x² − 2xy + y² when x = 10 and y = 2.
  18. 18.Use a² − b² = (a + b)(a − b) to find 53² − 47².
  19. 19.If a + b = 6 and ab = 5, what is a² + b²?
  20. 20.Use (a + b)² = a² + 2ab + b² to find 97².
  21. 21.Use a² − b² = (a + b)(a − b) to find 29² − 5².
  22. 22.Use (a + b)(a − b) = a² − b² to find 93 × 87.
  23. 23.Find the value of x² − 2xy + y² when x = 10 and y = 1.
  24. 24.Use a² − b² = (a + b)(a − b) to find 39² − 10².
  25. 25.Use (a + b)(a − b) = a² − b² to find 79 × 61.
  26. 26.If a + b = 9 and ab = 8, what is a² + b²?
  27. 27.Use (a − b)² = a² − 2ab + b² to find 32².
  28. 28.If a + b = 3 and ab = 2, what is a² + b²?
  29. 29.Use a² − b² = (a + b)(a − b) to find 34² − 30².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 26².
  31. 31.Use a² − b² = (a + b)(a − b) to find 57² − 14².
  32. 32.Use (a + b)(a − b) = a² − b² to find 41 × 39.
  33. 33.Use (a − b)² = a² − 2ab + b² to find 44².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 12².
  35. 35.Use a² − b² = (a + b)(a − b) to find 82² − 13².
  36. 36.Use a² − b² = (a + b)(a − b) to find 32² − 1².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 37².
  38. 38.Use (a + b)(a − b) = a² − b² to find 105 × 95.
  39. 39.If a + b = 15 and ab = 44, what is a² + b²?
  40. 40.Use (a + b)(a − b) = a² − b² to find 49 × 31.

Answer key

  1. 484
  2. 26
  3. 4624
  4. 4096
  5. 25
  6. 1369
  7. 2475
  8. 1024
  9. 961
  10. 17
  11. 576
  12. 29
  13. 13
  14. 10
  15. 351
  16. 7744
  17. 64
  18. 600
  19. 26
  20. 9409
  21. 816
  22. 8091
  23. 81
  24. 1421
  25. 4819
  26. 65
  27. 1024
  28. 5
  29. 256
  30. 676
  31. 3053
  32. 1599
  33. 1936
  34. 144
  35. 6555
  36. 1023
  37. 1369
  38. 9975
  39. 137
  40. 1519

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