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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 413 · 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 a² − b² = (a + b)(a − b) to find 55² − 3².
  2. 2.Find the value of x² − y² when x = 10 and y = 5.
  3. 3.Use (a + b)² = a² + 2ab + b² to find 46².
  4. 4.Use (a + b)(a − b) = a² − b² to find 41 × 39.
  5. 5.Use (a + b)² = a² + 2ab + b² to find 81².
  6. 6.Use (a + b)(a − b) = a² − b² to find 64 × 56.
  7. 7.Find the value of x² − 2xy + y² when x = 13 and y = 10.
  8. 8.Use a² − b² = (a + b)(a − b) to find 40² − 25².
  9. 9.Use (a + b)(a − b) = a² − b² to find 107 × 93.
  10. 10.Use (a + b)(a − b) = a² − b² to find 102 × 98.
  11. 11.Use (a + b)² = a² + 2ab + b² to find 56².
  12. 12.Use a² − b² = (a + b)(a − b) to find 98² − 94².
  13. 13.Find the value of x² − 2xy + y² when x = 4 and y = 2.
  14. 14.Find the value of x² + 2xy + y² when x = 8 and y = 7.
  15. 15.Use (a + b)(a − b) = a² − b² to find 76 × 64.
  16. 16.Use a² − b² = (a + b)(a − b) to find 59² − 31².
  17. 17.If a + b = 18 and ab = 80, what is a² + b²?
  18. 18.Use (a + b)(a − b) = a² − b² to find 93 × 87.
  19. 19.Use (a + b)² = a² + 2ab + b² to find 22².
  20. 20.Find the value of x² − 2xy + y² when x = 15 and y = 5.
  21. 21.Use (a + b)² = a² + 2ab + b² to find 91².
  22. 22.Find the value of x² − 2xy + y² when x = 8 and y = 5.
  23. 23.Use (a − b)² = a² − 2ab + b² to find 13².
  24. 24.Use a² − b² = (a + b)(a − b) to find 42² − 10².
  25. 25.If a + b = 4 and ab = 3, what is a² + b²?
  26. 26.Use (a + b)(a − b) = a² − b² to find 66 × 54.
  27. 27.Use (a + b)(a − b) = a² − b² to find 81 × 79.
  28. 28.Use (a − b)² = a² − 2ab + b² to find 56².
  29. 29.Use (a − b)² = a² − 2ab + b² to find 31².
  30. 30.Find the value of x² − y² when x = 7 and y = 3.
  31. 31.If a + b = 10 and ab = 24, what is a² + b²?
  32. 32.Use (a − b)² = a² − 2ab + b² to find 97².
  33. 33.If a − b = 2 and ab = 8, what is a² + b²?
  34. 34.Use a² − b² = (a + b)(a − b) to find 60² − 5².
  35. 35.Use (a − b)² = a² − 2ab + b² to find 99².
  36. 36.Use (a + b)(a − b) = a² − b² to find 68 × 52.
  37. 37.Find the value of x² − y² when x = 9 and y = 3.
  38. 38.Use a² − b² = (a + b)(a − b) to find 67² − 23².
  39. 39.Use a² − b² = (a + b)(a − b) to find 89² − 29².
  40. 40.Use (a − b)² = a² − 2ab + b² to find 71².

Answer key

  1. 3016
  2. 75
  3. 2116
  4. 1599
  5. 6561
  6. 3584
  7. 9
  8. 975
  9. 9951
  10. 9996
  11. 3136
  12. 768
  13. 4
  14. 225
  15. 4864
  16. 2520
  17. 164
  18. 8091
  19. 484
  20. 100
  21. 8281
  22. 9
  23. 169
  24. 1664
  25. 10
  26. 3564
  27. 6399
  28. 3136
  29. 961
  30. 40
  31. 52
  32. 9409
  33. 20
  34. 3575
  35. 9801
  36. 3536
  37. 72
  38. 3960
  39. 7080
  40. 5041

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