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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 853 · 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.Find the value of x² + 2xy + y² when x = 6 and y = 5.
  2. 2.If a + b = 16 and ab = 60, what is a² + b²?
  3. 3.If a + b = 3 and ab = 2, what is a² + b²?
  4. 4.Use (a + b)² = a² + 2ab + b² to find 51².
  5. 5.Use (a + b)² = a² + 2ab + b² to find 94².
  6. 6.If a + b = 12 and ab = 11, what is a² + b²?
  7. 7.Find the value of x² − 2xy + y² when x = 15 and y = 4.
  8. 8.Use (a − b)² = a² − 2ab + b² to find 39².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 89².
  10. 10.If a − b = 1 and ab = 90, what is a² + b²?
  11. 11.Use (a − b)² = a² − 2ab + b² to find 27².
  12. 12.Use (a + b)² = a² + 2ab + b² to find 93².
  13. 13.Use a² − b² = (a + b)(a − b) to find 40² − 17².
  14. 14.Use a² − b² = (a + b)(a − b) to find 66² − 65².
  15. 15.Use (a + b)(a − b) = a² − b² to find 62 × 58.
  16. 16.Find the value of x² − y² when x = 15 and y = 6.
  17. 17.Use (a + b)(a − b) = a² − b² to find 55 × 45.
  18. 18.Use (a + b)² = a² + 2ab + b² to find 43².
  19. 19.Use a² − b² = (a + b)(a − b) to find 30² − 13².
  20. 20.Find the value of x² − y² when x = 7 and y = 2.
  21. 21.Use (a + b)² = a² + 2ab + b² to find 82².
  22. 22.Use (a − b)² = a² − 2ab + b² to find 17².
  23. 23.Find the value of x² + 2xy + y² when x = 4 and y = 1.
  24. 24.Use a² − b² = (a + b)(a − b) to find 92² − 48².
  25. 25.Use a² − b² = (a + b)(a − b) to find 22² − 6².
  26. 26.If a + b = 9 and ab = 20, what is a² + b²?
  27. 27.Use (a − b)² = a² − 2ab + b² to find 89².
  28. 28.Use a² − b² = (a + b)(a − b) to find 40² − 13².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 95².
  30. 30.Use (a + b)(a − b) = a² − b² to find 74 × 66.
  31. 31.Use (a + b)² = a² + 2ab + b² to find 107².
  32. 32.Use (a + b)(a − b) = a² − b² to find 54 × 46.
  33. 33.Find the value of x² + 2xy + y² when x = 11 and y = 9.
  34. 34.Use a² − b² = (a + b)(a − b) to find 54² − 53².
  35. 35.If a + b = 8 and ab = 12, what is a² + b²?
  36. 36.Use a² − b² = (a + b)(a − b) to find 64² − 5².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 75².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 92².
  39. 39.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  40. 40.Use a² − b² = (a + b)(a − b) to find 81² − 45².

Answer key

  1. 121
  2. 136
  3. 5
  4. 2601
  5. 8836
  6. 122
  7. 121
  8. 1521
  9. 7921
  10. 181
  11. 729
  12. 8649
  13. 1311
  14. 131
  15. 3596
  16. 189
  17. 2475
  18. 1849
  19. 731
  20. 45
  21. 6724
  22. 289
  23. 25
  24. 6160
  25. 448
  26. 41
  27. 7921
  28. 1431
  29. 9025
  30. 4884
  31. 11449
  32. 2484
  33. 400
  34. 107
  35. 40
  36. 4071
  37. 5625
  38. 8464
  39. 25
  40. 4536

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