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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 964 · 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 44 × 36.
  2. 2.Use (a + b)² = a² + 2ab + b² to find 89².
  3. 3.Use (a + b)² = a² + 2ab + b² to find 22².
  4. 4.Find the value of x² − y² when x = 7 and y = 3.
  5. 5.Use (a + b)² = a² + 2ab + b² to find 109².
  6. 6.Use a² − b² = (a + b)(a − b) to find 36² − 8².
  7. 7.Use (a + b)(a − b) = a² − b² to find 92 × 88.
  8. 8.Use (a + b)(a − b) = a² − b² to find 109 × 91.
  9. 9.If a − b = 1 and ab = 2, what is a² + b²?
  10. 10.Use (a + b)(a − b) = a² − b² to find 81 × 79.
  11. 11.Use a² − b² = (a + b)(a − b) to find 56² − 26².
  12. 12.Use (a + b)² = a² + 2ab + b² to find 39².
  13. 13.Use (a + b)(a − b) = a² − b² to find 67 × 53.
  14. 14.Use (a + b)² = a² + 2ab + b² to find 53².
  15. 15.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  16. 16.If a + b = 18 and ab = 80, what is a² + b²?
  17. 17.Find the value of x² − 2xy + y² when x = 6 and y = 5.
  18. 18.Use (a − b)² = a² − 2ab + b² to find 34².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 81².
  20. 20.Use (a + b)² = a² + 2ab + b² to find 68².
  21. 21.Use (a − b)² = a² − 2ab + b² to find 24².
  22. 22.Use (a − b)² = a² − 2ab + b² to find 59².
  23. 23.Use (a + b)² = a² + 2ab + b² to find 41².
  24. 24.Find the value of x² − 2xy + y² when x = 11 and y = 5.
  25. 25.Use (a + b)(a − b) = a² − b² to find 103 × 97.
  26. 26.Use (a − b)² = a² − 2ab + b² to find 85².
  27. 27.Use (a + b)(a − b) = a² − b² to find 93 × 87.
  28. 28.If a − b = 2 and ab = 3, what is a² + b²?
  29. 29.Use (a + b)² = a² + 2ab + b² to find 99².
  30. 30.Use (a + b)(a − b) = a² − b² to find 91 × 89.
  31. 31.Use (a + b)(a − b) = a² − b² to find 77 × 63.
  32. 32.Find the value of x² + 2xy + y² when x = 13 and y = 11.
  33. 33.If a + b = 15 and ab = 54, what is a² + b²?
  34. 34.Find the value of x² − 2xy + y² when x = 15 and y = 3.
  35. 35.Find the value of x² + 2xy + y² when x = 15 and y = 1.
  36. 36.Use (a + b)(a − b) = a² − b² to find 41 × 39.
  37. 37.Use (a + b)(a − b) = a² − b² to find 71 × 69.
  38. 38.If a + b = 15 and ab = 56, what is a² + b²?
  39. 39.Use (a − b)² = a² − 2ab + b² to find 94².
  40. 40.Use (a + b)² = a² + 2ab + b² to find 27².

Answer key

  1. 1584
  2. 7921
  3. 484
  4. 40
  5. 11881
  6. 1232
  7. 8096
  8. 9919
  9. 5
  10. 6399
  11. 2460
  12. 1521
  13. 3551
  14. 2809
  15. 1591
  16. 164
  17. 1
  18. 1156
  19. 6561
  20. 4624
  21. 576
  22. 3481
  23. 1681
  24. 36
  25. 9991
  26. 7225
  27. 8091
  28. 10
  29. 9801
  30. 8099
  31. 4851
  32. 576
  33. 117
  34. 144
  35. 256
  36. 1599
  37. 4899
  38. 113
  39. 8836
  40. 729

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