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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 831 · 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.If a + b = 14 and ab = 48, what is a² + b²?
  2. 2.If a + b = 8 and ab = 7, what is a² + b²?
  3. 3.Use (a + b)(a − b) = a² − b² to find 103 × 97.
  4. 4.Find the value of x² + 2xy + y² when x = 10 and y = 3.
  5. 5.Use (a + b)(a − b) = a² − b² to find 29 × 11.
  6. 6.Use a² − b² = (a + b)(a − b) to find 83² − 19².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 42².
  8. 8.Use (a − b)² = a² − 2ab + b² to find 65².
  9. 9.Find the value of x² + 2xy + y² when x = 7 and y = 5.
  10. 10.Use (a + b)² = a² + 2ab + b² to find 69².
  11. 11.Use (a + b)² = a² + 2ab + b² to find 104².
  12. 12.Find the value of x² + 2xy + y² when x = 13 and y = 11.
  13. 13.Use (a − b)² = a² − 2ab + b² to find 62².
  14. 14.Use (a + b)² = a² + 2ab + b² to find 103².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 77².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 56².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 12².
  18. 18.Use a² − b² = (a + b)(a − b) to find 59² − 54².
  19. 19.If a + b = 12 and ab = 35, what is a² + b²?
  20. 20.Use a² − b² = (a + b)(a − b) to find 23² − 5².
  21. 21.Use a² − b² = (a + b)(a − b) to find 73² − 15².
  22. 22.Use (a − b)² = a² − 2ab + b² to find 54².
  23. 23.Use (a − b)² = a² − 2ab + b² to find 99².
  24. 24.Use (a + b)(a − b) = a² − b² to find 28 × 12.
  25. 25.Use (a + b)² = a² + 2ab + b² to find 46².
  26. 26.Use a² − b² = (a + b)(a − b) to find 82² − 37².
  27. 27.If a − b = 1 and ab = 2, what is a² + b²?
  28. 28.If a + b = 8 and ab = 12, what is a² + b²?
  29. 29.If a − b = 7 and ab = 18, what is a² + b²?
  30. 30.Use (a + b)(a − b) = a² − b² to find 83 × 77.
  31. 31.Use a² − b² = (a + b)(a − b) to find 26² − 2².
  32. 32.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  33. 33.Use (a − b)² = a² − 2ab + b² to find 32².
  34. 34.Use a² − b² = (a + b)(a − b) to find 48² − 33².
  35. 35.Use (a + b)² = a² + 2ab + b² to find 16².
  36. 36.Use (a + b)(a − b) = a² − b² to find 106 × 94.
  37. 37.Use (a + b)² = a² + 2ab + b² to find 55².
  38. 38.Use a² − b² = (a + b)(a − b) to find 49² − 5².
  39. 39.Find the value of x² + 2xy + y² when x = 13 and y = 2.
  40. 40.Find the value of x² − y² when x = 4 and y = 2.

Answer key

  1. 100
  2. 50
  3. 9991
  4. 169
  5. 319
  6. 6528
  7. 1764
  8. 4225
  9. 144
  10. 4761
  11. 10816
  12. 576
  13. 3844
  14. 10609
  15. 5929
  16. 3136
  17. 144
  18. 565
  19. 74
  20. 504
  21. 5104
  22. 2916
  23. 9801
  24. 336
  25. 2116
  26. 5355
  27. 5
  28. 40
  29. 85
  30. 6391
  31. 672
  32. 25
  33. 1024
  34. 1215
  35. 256
  36. 9964
  37. 3025
  38. 2376
  39. 225
  40. 12

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