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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 886 · 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 33².
  2. 2.Find the value of x² + 2xy + y² when x = 3 and y = 1.
  3. 3.If a + b = 8 and ab = 7, what is a² + b²?
  4. 4.Find the value of x² − 2xy + y² when x = 3 and y = 2.
  5. 5.Use a² − b² = (a + b)(a − b) to find 66² − 48².
  6. 6.Use (a + b)(a − b) = a² − b² to find 33 × 27.
  7. 7.Use (a − b)² = a² − 2ab + b² to find 51².
  8. 8.Use (a + b)² = a² + 2ab + b² to find 41².
  9. 9.Use (a + b)(a − b) = a² − b² to find 101 × 99.
  10. 10.If a + b = 17 and ab = 66, what is a² + b²?
  11. 11.Use a² − b² = (a + b)(a − b) to find 88² − 22².
  12. 12.Use (a + b)(a − b) = a² − b² to find 39 × 21.
  13. 13.Use (a + b)(a − b) = a² − b² to find 83 × 77.
  14. 14.Use a² − b² = (a + b)(a − b) to find 45² − 42².
  15. 15.Use a² − b² = (a + b)(a − b) to find 52² − 24².
  16. 16.If a + b = 21 and ab = 110, what is a² + b²?
  17. 17.If a − b = 5 and ab = 66, what is a² + b²?
  18. 18.Use (a − b)² = a² − 2ab + b² to find 65².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 19².
  20. 20.If a − b = 2 and ab = 8, what is a² + b²?
  21. 21.Use (a + b)² = a² + 2ab + b² to find 29².
  22. 22.If a − b = 2 and ab = 24, what is a² + b²?
  23. 23.Use a² − b² = (a + b)(a − b) to find 24² − 1².
  24. 24.Use (a + b)(a − b) = a² − b² to find 78 × 62.
  25. 25.Use (a + b)(a − b) = a² − b² to find 44 × 36.
  26. 26.Use (a + b)(a − b) = a² − b² to find 25 × 15.
  27. 27.Use (a + b)(a − b) = a² − b² to find 87 × 73.
  28. 28.If a + b = 9 and ab = 14, what is a² + b²?
  29. 29.Use a² − b² = (a + b)(a − b) to find 59² − 38².
  30. 30.Find the value of x² + 2xy + y² when x = 7 and y = 2.
  31. 31.Use (a − b)² = a² − 2ab + b² to find 98².
  32. 32.Use (a − b)² = a² − 2ab + b² to find 52².
  33. 33.Use a² − b² = (a + b)(a − b) to find 63² − 54².
  34. 34.Use a² − b² = (a + b)(a − b) to find 63² − 19².
  35. 35.Use a² − b² = (a + b)(a − b) to find 92² − 26².
  36. 36.Use (a + b)² = a² + 2ab + b² to find 69².
  37. 37.Use a² − b² = (a + b)(a − b) to find 34² − 26².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 25².
  39. 39.If a − b = 1 and ab = 12, what is a² + b²?
  40. 40.Use (a − b)² = a² − 2ab + b² to find 18².

Answer key

  1. 1089
  2. 16
  3. 50
  4. 1
  5. 2052
  6. 891
  7. 2601
  8. 1681
  9. 9999
  10. 157
  11. 7260
  12. 819
  13. 6391
  14. 261
  15. 2128
  16. 221
  17. 157
  18. 4225
  19. 361
  20. 20
  21. 841
  22. 52
  23. 575
  24. 4836
  25. 1584
  26. 375
  27. 6351
  28. 53
  29. 2037
  30. 81
  31. 9604
  32. 2704
  33. 1053
  34. 3608
  35. 7788
  36. 4761
  37. 480
  38. 625
  39. 25
  40. 324

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