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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 947 · 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.Find the value of x² + 2xy + y² when x = 4 and y = 1.
  2. 2.Use (a + b)(a − b) = a² − b² to find 62 × 58.
  3. 3.Use (a + b)² = a² + 2ab + b² to find 65².
  4. 4.Use (a − b)² = a² − 2ab + b² to find 86².
  5. 5.Use a² − b² = (a + b)(a − b) to find 30² − 9².
  6. 6.If a − b = 1 and ab = 30, what is a² + b²?
  7. 7.If a − b = 1 and ab = 20, what is a² + b²?
  8. 8.Use (a − b)² = a² − 2ab + b² to find 95².
  9. 9.Use a² − b² = (a + b)(a − b) to find 57² − 11².
  10. 10.Find the value of x² + 2xy + y² when x = 6 and y = 2.
  11. 11.Find the value of x² − y² when x = 5 and y = 3.
  12. 12.If a − b = 5 and ab = 24, what is a² + b²?
  13. 13.Find the value of x² + 2xy + y² when x = 9 and y = 5.
  14. 14.Use (a − b)² = a² − 2ab + b² to find 84².
  15. 15.Use (a + b)² = a² + 2ab + b² to find 72².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 82².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 92².
  18. 18.Use (a + b)² = a² + 2ab + b² to find 94².
  19. 19.Use a² − b² = (a + b)(a − b) to find 87² − 55².
  20. 20.Use (a + b)(a − b) = a² − b² to find 67 × 53.
  21. 21.Use (a + b)(a − b) = a² − b² to find 66 × 54.
  22. 22.If a + b = 9 and ab = 20, what is a² + b²?
  23. 23.Use (a + b)(a − b) = a² − b² to find 33 × 27.
  24. 24.Use (a + b)² = a² + 2ab + b² to find 32².
  25. 25.If a − b = 2 and ab = 48, what is a² + b²?
  26. 26.Use (a + b)² = a² + 2ab + b² to find 42².
  27. 27.Use (a + b)² = a² + 2ab + b² to find 73².
  28. 28.Use a² − b² = (a + b)(a − b) to find 36² − 32².
  29. 29.Use (a + b)(a − b) = a² − b² to find 107 × 93.
  30. 30.Use (a + b)(a − b) = a² − b² to find 37 × 23.
  31. 31.Use (a + b)(a − b) = a² − b² to find 76 × 64.
  32. 32.Use (a − b)² = a² − 2ab + b² to find 89².
  33. 33.Use a² − b² = (a + b)(a − b) to find 76² − 75².
  34. 34.Use (a + b)(a − b) = a² − b² to find 106 × 94.
  35. 35.Use a² − b² = (a + b)(a − b) to find 90² − 77².
  36. 36.Use (a − b)² = a² − 2ab + b² to find 11².
  37. 37.Use (a + b)(a − b) = a² − b² to find 87 × 73.
  38. 38.Use (a + b)(a − b) = a² − b² to find 28 × 12.
  39. 39.Use (a − b)² = a² − 2ab + b² to find 94².
  40. 40.Use a² − b² = (a + b)(a − b) to find 95² − 42².

Answer key

  1. 25
  2. 3596
  3. 4225
  4. 7396
  5. 819
  6. 61
  7. 41
  8. 9025
  9. 3128
  10. 64
  11. 16
  12. 73
  13. 196
  14. 7056
  15. 5184
  16. 6724
  17. 8464
  18. 8836
  19. 4544
  20. 3551
  21. 3564
  22. 41
  23. 891
  24. 1024
  25. 100
  26. 1764
  27. 5329
  28. 272
  29. 9951
  30. 851
  31. 4864
  32. 7921
  33. 151
  34. 9964
  35. 2171
  36. 121
  37. 6351
  38. 336
  39. 8836
  40. 7261

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