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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 351 · 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 67 × 53.
  2. 2.Use (a − b)² = a² − 2ab + b² to find 35².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 18².
  4. 4.Use (a + b)(a − b) = a² − b² to find 47 × 33.
  5. 5.If a + b = 3 and ab = 2, what is a² + b²?
  6. 6.If a − b = 2 and ab = 8, what is a² + b²?
  7. 7.If a + b = 4 and ab = 3, what is a² + b²?
  8. 8.Find the value of x² − y² when x = 6 and y = 1.
  9. 9.Use a² − b² = (a + b)(a − b) to find 54² − 44².
  10. 10.Use (a + b)(a − b) = a² − b² to find 44 × 36.
  11. 11.Use (a − b)² = a² − 2ab + b² to find 27².
  12. 12.Find the value of x² + 2xy + y² when x = 15 and y = 3.
  13. 13.Use (a − b)² = a² − 2ab + b² to find 94².
  14. 14.Use (a − b)² = a² − 2ab + b² to find 95².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 16².
  16. 16.Use (a + b)(a − b) = a² − b² to find 32 × 28.
  17. 17.Find the value of x² − 2xy + y² when x = 12 and y = 6.
  18. 18.Find the value of x² + 2xy + y² when x = 10 and y = 2.
  19. 19.Use (a + b)(a − b) = a² − b² to find 63 × 57.
  20. 20.Find the value of x² + 2xy + y² when x = 11 and y = 7.
  21. 21.If a − b = 1 and ab = 2, what is a² + b²?
  22. 22.Use (a − b)² = a² − 2ab + b² to find 57².
  23. 23.Use (a − b)² = a² − 2ab + b² to find 45².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 33².
  25. 25.Use (a − b)² = a² − 2ab + b² to find 11².
  26. 26.Use (a − b)² = a² − 2ab + b² to find 39².
  27. 27.Use (a + b)(a − b) = a² − b² to find 91 × 89.
  28. 28.Use (a + b)² = a² + 2ab + b² to find 102².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 14².
  30. 30.Use (a + b)(a − b) = a² − b² to find 33 × 27.
  31. 31.Use a² − b² = (a + b)(a − b) to find 58² − 16².
  32. 32.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  33. 33.Use (a + b)(a − b) = a² − b² to find 23 × 17.
  34. 34.Use (a + b)² = a² + 2ab + b² to find 74².
  35. 35.Use a² − b² = (a + b)(a − b) to find 59² − 28².
  36. 36.Use a² − b² = (a + b)(a − b) to find 81² − 59².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 84².
  38. 38.Use a² − b² = (a + b)(a − b) to find 88² − 13².
  39. 39.If a − b = 7 and ab = 8, what is a² + b²?
  40. 40.Use a² − b² = (a + b)(a − b) to find 41² − 1².

Answer key

  1. 3551
  2. 1225
  3. 324
  4. 1551
  5. 5
  6. 20
  7. 10
  8. 35
  9. 980
  10. 1584
  11. 729
  12. 324
  13. 8836
  14. 9025
  15. 256
  16. 896
  17. 36
  18. 144
  19. 3591
  20. 324
  21. 5
  22. 3249
  23. 2025
  24. 1089
  25. 121
  26. 1521
  27. 8099
  28. 10404
  29. 196
  30. 891
  31. 3108
  32. 1591
  33. 391
  34. 5476
  35. 2697
  36. 3080
  37. 7056
  38. 7575
  39. 65
  40. 1680

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