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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 235 · 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 63².
  2. 2.Use a² − b² = (a + b)(a − b) to find 72² − 44².
  3. 3.Use a² − b² = (a + b)(a − b) to find 63² − 6².
  4. 4.Use a² − b² = (a + b)(a − b) to find 91² − 59².
  5. 5.If a + b = 3 and ab = 2, what is a² + b²?
  6. 6.Use a² − b² = (a + b)(a − b) to find 60² − 4².
  7. 7.If a − b = 7 and ab = 60, what is a² + b²?
  8. 8.Find the value of x² + 2xy + y² when x = 15 and y = 8.
  9. 9.Use a² − b² = (a + b)(a − b) to find 23² − 22².
  10. 10.Use (a + b)(a − b) = a² − b² to find 106 × 94.
  11. 11.Use (a − b)² = a² − 2ab + b² to find 31².
  12. 12.Find the value of x² − 2xy + y² when x = 8 and y = 7.
  13. 13.Use (a + b)(a − b) = a² − b² to find 102 × 98.
  14. 14.Use (a − b)² = a² − 2ab + b² to find 93².
  15. 15.Use a² − b² = (a + b)(a − b) to find 72² − 53².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 45².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 21².
  18. 18.If a − b = 6 and ab = 27, what is a² + b²?
  19. 19.Use (a + b)² = a² + 2ab + b² to find 41².
  20. 20.Use (a + b)(a − b) = a² − b² to find 56 × 44.
  21. 21.Use (a − b)² = a² − 2ab + b² to find 33².
  22. 22.Use (a + b)(a − b) = a² − b² to find 26 × 14.
  23. 23.Use (a − b)² = a² − 2ab + b² to find 92².
  24. 24.Use (a − b)² = a² − 2ab + b² to find 19².
  25. 25.Use (a + b)² = a² + 2ab + b² to find 73².
  26. 26.Use a² − b² = (a + b)(a − b) to find 62² − 60².
  27. 27.Use (a − b)² = a² − 2ab + b² to find 83².
  28. 28.Find the value of x² − 2xy + y² when x = 13 and y = 12.
  29. 29.Use (a + b)(a − b) = a² − b² to find 65 × 55.
  30. 30.Use a² − b² = (a + b)(a − b) to find 33² − 17².
  31. 31.Use a² − b² = (a + b)(a − b) to find 77² − 46².
  32. 32.Use (a + b)(a − b) = a² − b² to find 42 × 38.
  33. 33.Use (a + b)(a − b) = a² − b² to find 27 × 13.
  34. 34.Find the value of x² − y² when x = 13 and y = 10.
  35. 35.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  36. 36.If a − b = 4 and ab = 21, what is a² + b²?
  37. 37.Use a² − b² = (a + b)(a − b) to find 47² − 14².
  38. 38.Use (a + b)² = a² + 2ab + b² to find 18².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 34².
  40. 40.Use (a + b)² = a² + 2ab + b² to find 32².

Answer key

  1. 3969
  2. 3248
  3. 3933
  4. 4800
  5. 5
  6. 3584
  7. 169
  8. 529
  9. 45
  10. 9964
  11. 961
  12. 1
  13. 9996
  14. 8649
  15. 2375
  16. 2025
  17. 441
  18. 90
  19. 1681
  20. 2464
  21. 1089
  22. 364
  23. 8464
  24. 361
  25. 5329
  26. 244
  27. 6889
  28. 1
  29. 3575
  30. 800
  31. 3813
  32. 1596
  33. 351
  34. 69
  35. 25
  36. 58
  37. 2013
  38. 324
  39. 1156
  40. 1024

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