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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 486 · 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 26 × 14.
  2. 2.Use a² − b² = (a + b)(a − b) to find 52² − 50².
  3. 3.Use a² − b² = (a + b)(a − b) to find 63² − 36².
  4. 4.If a − b = 2 and ab = 3, what is a² + b²?
  5. 5.Use (a + b)² = a² + 2ab + b² to find 23².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 37².
  7. 7.Find the value of x² − y² when x = 11 and y = 10.
  8. 8.Use (a − b)² = a² − 2ab + b² to find 57².
  9. 9.Use (a + b)(a − b) = a² − b² to find 87 × 73.
  10. 10.Find the value of x² − y² when x = 9 and y = 8.
  11. 11.Use a² − b² = (a + b)(a − b) to find 86² − 66².
  12. 12.If a + b = 13 and ab = 42, what is a² + b²?
  13. 13.Use a² − b² = (a + b)(a − b) to find 45² − 17².
  14. 14.Use (a − b)² = a² − 2ab + b² to find 65².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 89².
  16. 16.If a − b = 1 and ab = 12, what is a² + b²?
  17. 17.Use (a + b)² = a² + 2ab + b² to find 18².
  18. 18.Use (a + b)(a − b) = a² − b² to find 104 × 96.
  19. 19.Use a² − b² = (a + b)(a − b) to find 72² − 67².
  20. 20.Find the value of x² + 2xy + y² when x = 9 and y = 2.
  21. 21.Use (a + b)² = a² + 2ab + b² to find 51².
  22. 22.Use (a + b)(a − b) = a² − b² to find 41 × 39.
  23. 23.Find the value of x² − y² when x = 4 and y = 3.
  24. 24.Use a² − b² = (a + b)(a − b) to find 96² − 65².
  25. 25.If a − b = 4 and ab = 32, what is a² + b²?
  26. 26.Use a² − b² = (a + b)(a − b) to find 98² − 10².
  27. 27.Use a² − b² = (a + b)(a − b) to find 45² − 33².
  28. 28.Find the value of x² − 2xy + y² when x = 9 and y = 5.
  29. 29.If a + b = 13 and ab = 30, what is a² + b²?
  30. 30.Use (a + b)² = a² + 2ab + b² to find 15².
  31. 31.Use (a − b)² = a² − 2ab + b² to find 25².
  32. 32.If a + b = 5 and ab = 4, what is a² + b²?
  33. 33.Use (a − b)² = a² − 2ab + b² to find 92².
  34. 34.Use (a + b)(a − b) = a² − b² to find 53 × 47.
  35. 35.Use (a + b)² = a² + 2ab + b² to find 101².
  36. 36.If a − b = 2 and ab = 24, what is a² + b²?
  37. 37.Use (a − b)² = a² − 2ab + b² to find 17².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 52².
  39. 39.Use a² − b² = (a + b)(a − b) to find 69² − 28².
  40. 40.Use (a + b)² = a² + 2ab + b² to find 12².

Answer key

  1. 364
  2. 204
  3. 2673
  4. 10
  5. 529
  6. 1369
  7. 21
  8. 3249
  9. 6351
  10. 17
  11. 3040
  12. 85
  13. 1736
  14. 4225
  15. 7921
  16. 25
  17. 324
  18. 9984
  19. 695
  20. 121
  21. 2601
  22. 1599
  23. 7
  24. 4991
  25. 80
  26. 9504
  27. 936
  28. 16
  29. 109
  30. 225
  31. 625
  32. 17
  33. 8464
  34. 2491
  35. 10201
  36. 52
  37. 289
  38. 2704
  39. 3977
  40. 144

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