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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 660 · 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 36 × 24.
  2. 2.Use (a − b)² = a² − 2ab + b² to find 27².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 37².
  4. 4.Use (a − b)² = a² − 2ab + b² to find 45².
  5. 5.Use a² − b² = (a + b)(a − b) to find 89² − 13².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 84².
  7. 7.If a + b = 10 and ab = 9, what is a² + b²?
  8. 8.If a − b = 5 and ab = 6, what is a² + b²?
  9. 9.Use (a + b)² = a² + 2ab + b² to find 12².
  10. 10.If a − b = 3 and ab = 10, what is a² + b²?
  11. 11.Find the value of x² + 2xy + y² when x = 8 and y = 7.
  12. 12.Use (a − b)² = a² − 2ab + b² to find 89².
  13. 13.Use (a + b)² = a² + 2ab + b² to find 41².
  14. 14.Use (a + b)(a − b) = a² − b² to find 61 × 59.
  15. 15.Use (a + b)(a − b) = a² − b² to find 42 × 38.
  16. 16.Use a² − b² = (a + b)(a − b) to find 91² − 15².
  17. 17.If a + b = 3 and ab = 2, what is a² + b²?
  18. 18.Use a² − b² = (a + b)(a − b) to find 36² − 9².
  19. 19.If a − b = 1 and ab = 6, what is a² + b²?
  20. 20.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  21. 21.Use a² − b² = (a + b)(a − b) to find 46² − 40².
  22. 22.Find the value of x² − y² when x = 5 and y = 2.
  23. 23.Find the value of x² + 2xy + y² when x = 13 and y = 12.
  24. 24.Use (a + b)(a − b) = a² − b² to find 41 × 39.
  25. 25.Use a² − b² = (a + b)(a − b) to find 92² − 91².
  26. 26.Use (a + b)² = a² + 2ab + b² to find 51².
  27. 27.Use (a + b)(a − b) = a² − b² to find 45 × 35.
  28. 28.Use (a + b)² = a² + 2ab + b² to find 42².
  29. 29.Find the value of x² + 2xy + y² when x = 12 and y = 11.
  30. 30.Use (a + b)² = a² + 2ab + b² to find 32².
  31. 31.Use (a + b)(a − b) = a² − b² to find 62 × 58.
  32. 32.Use (a + b)² = a² + 2ab + b² to find 27².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 88².
  34. 34.Use (a − b)² = a² − 2ab + b² to find 92².
  35. 35.Use (a + b)² = a² + 2ab + b² to find 43².
  36. 36.Use (a − b)² = a² − 2ab + b² to find 24².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 32².
  38. 38.Use (a + b)² = a² + 2ab + b² to find 107².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 55².
  40. 40.Find the value of x² − y² when x = 13 and y = 2.

Answer key

  1. 864
  2. 729
  3. 1369
  4. 2025
  5. 7752
  6. 7056
  7. 82
  8. 37
  9. 144
  10. 29
  11. 225
  12. 7921
  13. 1681
  14. 3599
  15. 1596
  16. 8056
  17. 5
  18. 1215
  19. 13
  20. 25
  21. 516
  22. 21
  23. 625
  24. 1599
  25. 183
  26. 2601
  27. 1575
  28. 1764
  29. 529
  30. 1024
  31. 3596
  32. 729
  33. 7744
  34. 8464
  35. 1849
  36. 576
  37. 1024
  38. 11449
  39. 3025
  40. 165

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