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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 794 · 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.If a − b = 4 and ab = 5, what is a² + b²?
  2. 2.Use (a + b)(a − b) = a² − b² to find 78 × 62.
  3. 3.Find the value of x² − 2xy + y² when x = 5 and y = 4.
  4. 4.Find the value of x² + 2xy + y² when x = 9 and y = 3.
  5. 5.Use a² − b² = (a + b)(a − b) to find 43² − 11².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 52².
  7. 7.Use (a + b)(a − b) = a² − b² to find 47 × 33.
  8. 8.Use (a − b)² = a² − 2ab + b² to find 21².
  9. 9.If a + b = 21 and ab = 110, what is a² + b²?
  10. 10.If a − b = 5 and ab = 6, what is a² + b²?
  11. 11.Use a² − b² = (a + b)(a − b) to find 67² − 52².
  12. 12.Use (a + b)² = a² + 2ab + b² to find 95².
  13. 13.Use (a − b)² = a² − 2ab + b² to find 62².
  14. 14.Use (a + b)(a − b) = a² − b² to find 67 × 53.
  15. 15.Find the value of x² − 2xy + y² when x = 5 and y = 3.
  16. 16.Use (a − b)² = a² − 2ab + b² to find 35².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 31².
  18. 18.Use (a + b)² = a² + 2ab + b² to find 49².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 37².
  20. 20.If a − b = 7 and ab = 18, what is a² + b²?
  21. 21.Use a² − b² = (a + b)(a − b) to find 57² − 23².
  22. 22.Use (a + b)² = a² + 2ab + b² to find 35².
  23. 23.Find the value of x² − y² when x = 11 and y = 3.
  24. 24.Use (a + b)(a − b) = a² − b² to find 101 × 99.
  25. 25.Use (a − b)² = a² − 2ab + b² to find 69².
  26. 26.Use a² − b² = (a + b)(a − b) to find 63² − 50².
  27. 27.If a + b = 10 and ab = 9, what is a² + b²?
  28. 28.Find the value of x² − 2xy + y² when x = 8 and y = 1.
  29. 29.Use a² − b² = (a + b)(a − b) to find 36² − 23².
  30. 30.Use a² − b² = (a + b)(a − b) to find 49² − 8².
  31. 31.Find the value of x² − y² when x = 6 and y = 4.
  32. 32.Use a² − b² = (a + b)(a − b) to find 32² − 2².
  33. 33.Use a² − b² = (a + b)(a − b) to find 76² − 5².
  34. 34.Use a² − b² = (a + b)(a − b) to find 95² − 26².
  35. 35.If a + b = 12 and ab = 11, what is a² + b²?
  36. 36.Use (a + b)² = a² + 2ab + b² to find 83².
  37. 37.Use (a + b)(a − b) = a² − b² to find 62 × 58.
  38. 38.Use (a + b)² = a² + 2ab + b² to find 52².
  39. 39.Find the value of x² − y² when x = 7 and y = 2.
  40. 40.Use (a − b)² = a² − 2ab + b² to find 23².

Answer key

  1. 26
  2. 4836
  3. 1
  4. 144
  5. 1728
  6. 2704
  7. 1551
  8. 441
  9. 221
  10. 37
  11. 1785
  12. 9025
  13. 3844
  14. 3551
  15. 4
  16. 1225
  17. 961
  18. 2401
  19. 1369
  20. 85
  21. 2720
  22. 1225
  23. 112
  24. 9999
  25. 4761
  26. 1469
  27. 82
  28. 49
  29. 767
  30. 2337
  31. 20
  32. 1020
  33. 5751
  34. 8349
  35. 122
  36. 6889
  37. 3596
  38. 2704
  39. 45
  40. 529

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