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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 302 · 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 − 2xy + y² when x = 13 and y = 2.
  2. 2.If a + b = 15 and ab = 56, what is a² + b²?
  3. 3.Use (a + b)² = a² + 2ab + b² to find 23².
  4. 4.Use a² − b² = (a + b)(a − b) to find 55² − 17².
  5. 5.Use (a − b)² = a² − 2ab + b² to find 23².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 79².
  7. 7.Find the value of x² + 2xy + y² when x = 3 and y = 1.
  8. 8.Use (a − b)² = a² − 2ab + b² to find 96².
  9. 9.Use (a − b)² = a² − 2ab + b² to find 52².
  10. 10.Use (a + b)² = a² + 2ab + b² to find 16².
  11. 11.Use (a + b)² = a² + 2ab + b² to find 63².
  12. 12.Find the value of x² − 2xy + y² when x = 10 and y = 7.
  13. 13.Use (a + b)² = a² + 2ab + b² to find 56².
  14. 14.Use a² − b² = (a + b)(a − b) to find 89² − 28².
  15. 15.If a + b = 9 and ab = 20, what is a² + b²?
  16. 16.Use (a + b)(a − b) = a² − b² to find 83 × 77.
  17. 17.If a + b = 5 and ab = 6, what is a² + b²?
  18. 18.Use a² − b² = (a + b)(a − b) to find 47² − 20².
  19. 19.Find the value of x² − 2xy + y² when x = 12 and y = 8.
  20. 20.Use a² − b² = (a + b)(a − b) to find 89² − 51².
  21. 21.Use a² − b² = (a + b)(a − b) to find 79² − 16².
  22. 22.Use (a + b)² = a² + 2ab + b² to find 82².
  23. 23.If a − b = 2 and ab = 63, what is a² + b²?
  24. 24.If a − b = 1 and ab = 6, what is a² + b²?
  25. 25.Find the value of x² + 2xy + y² when x = 6 and y = 1.
  26. 26.Use a² − b² = (a + b)(a − b) to find 34² − 5².
  27. 27.Use (a + b)(a − b) = a² − b² to find 47 × 33.
  28. 28.Use (a − b)² = a² − 2ab + b² to find 69².
  29. 29.Use (a + b)(a − b) = a² − b² to find 59 × 41.
  30. 30.Use (a + b)(a − b) = a² − b² to find 24 × 16.
  31. 31.Use (a + b)(a − b) = a² − b² to find 81 × 79.
  32. 32.Use (a + b)² = a² + 2ab + b² to find 73².
  33. 33.Use (a + b)(a − b) = a² − b² to find 99 × 81.
  34. 34.Use (a − b)² = a² − 2ab + b² to find 83².
  35. 35.If a + b = 5 and ab = 4, what is a² + b²?
  36. 36.Use (a − b)² = a² − 2ab + b² to find 33².
  37. 37.If a − b = 3 and ab = 4, what is a² + b²?
  38. 38.Use (a + b)(a − b) = a² − b² to find 93 × 87.
  39. 39.Use a² − b² = (a + b)(a − b) to find 32² − 6².
  40. 40.Use a² − b² = (a + b)(a − b) to find 61² − 4².

Answer key

  1. 121
  2. 113
  3. 529
  4. 2736
  5. 529
  6. 6241
  7. 16
  8. 9216
  9. 2704
  10. 256
  11. 3969
  12. 9
  13. 3136
  14. 7137
  15. 41
  16. 6391
  17. 13
  18. 1809
  19. 16
  20. 5320
  21. 5985
  22. 6724
  23. 130
  24. 13
  25. 49
  26. 1131
  27. 1551
  28. 4761
  29. 2419
  30. 384
  31. 6399
  32. 5329
  33. 8019
  34. 6889
  35. 17
  36. 1089
  37. 17
  38. 8091
  39. 988
  40. 3705

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