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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 119 · 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.Find the value of x² − y² when x = 15 and y = 13.
  2. 2.Use a² − b² = (a + b)(a − b) to find 88² − 15².
  3. 3.Use (a + b)² = a² + 2ab + b² to find 22².
  4. 4.Find the value of x² + 2xy + y² when x = 5 and y = 1.
  5. 5.Use (a + b)² = a² + 2ab + b² to find 44².
  6. 6.If a − b = 3 and ab = 54, what is a² + b²?
  7. 7.Use a² − b² = (a + b)(a − b) to find 43² − 31².
  8. 8.Find the value of x² + 2xy + y² when x = 7 and y = 5.
  9. 9.Use (a − b)² = a² − 2ab + b² to find 15².
  10. 10.Use (a + b)(a − b) = a² − b² to find 27 × 13.
  11. 11.Use (a + b)² = a² + 2ab + b² to find 75².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 37².
  13. 13.Use (a − b)² = a² − 2ab + b² to find 12².
  14. 14.If a + b = 16 and ab = 60, what is a² + b²?
  15. 15.Use (a − b)² = a² − 2ab + b² to find 69².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 107².
  17. 17.Use (a + b)(a − b) = a² − b² to find 77 × 63.
  18. 18.Use (a − b)² = a² − 2ab + b² to find 62².
  19. 19.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  20. 20.Use (a + b)² = a² + 2ab + b² to find 12².
  21. 21.Use (a + b)(a − b) = a² − b² to find 37 × 23.
  22. 22.If a + b = 4 and ab = 3, what is a² + b²?
  23. 23.Find the value of x² − y² when x = 10 and y = 3.
  24. 24.If a + b = 10 and ab = 16, what is a² + b²?
  25. 25.Use a² − b² = (a + b)(a − b) to find 69² − 44².
  26. 26.Use (a − b)² = a² − 2ab + b² to find 82².
  27. 27.Find the value of x² − y² when x = 13 and y = 8.
  28. 28.Use (a − b)² = a² − 2ab + b² to find 94².
  29. 29.Use (a − b)² = a² − 2ab + b² to find 19².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 29².
  31. 31.Use (a − b)² = a² − 2ab + b² to find 88².
  32. 32.If a + b = 10 and ab = 21, what is a² + b²?
  33. 33.Use (a + b)(a − b) = a² − b² to find 22 × 18.
  34. 34.Use (a + b)² = a² + 2ab + b² to find 21².
  35. 35.Use (a + b)² = a² + 2ab + b² to find 53².
  36. 36.Use (a − b)² = a² − 2ab + b² to find 63².
  37. 37.Use (a + b)(a − b) = a² − b² to find 21 × 19.
  38. 38.Use a² − b² = (a + b)(a − b) to find 50² − 39².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 34².
  40. 40.If a − b = 2 and ab = 3, what is a² + b²?

Answer key

  1. 56
  2. 7519
  3. 484
  4. 36
  5. 1936
  6. 117
  7. 888
  8. 144
  9. 225
  10. 351
  11. 5625
  12. 1369
  13. 144
  14. 136
  15. 4761
  16. 11449
  17. 4851
  18. 3844
  19. 25
  20. 144
  21. 851
  22. 10
  23. 91
  24. 68
  25. 2825
  26. 6724
  27. 105
  28. 8836
  29. 361
  30. 841
  31. 7744
  32. 58
  33. 396
  34. 441
  35. 2809
  36. 3969
  37. 399
  38. 979
  39. 1156
  40. 10

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