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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 594 · 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)² = a² + 2ab + b² to find 38².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 94².
  3. 3.Use a² − b² = (a + b)(a − b) to find 23² − 6².
  4. 4.Use (a + b)(a − b) = a² − b² to find 103 × 97.
  5. 5.If a + b = 7 and ab = 12, what is a² + b²?
  6. 6.Use (a + b)(a − b) = a² − b² to find 66 × 54.
  7. 7.Use (a + b)² = a² + 2ab + b² to find 61².
  8. 8.Use a² − b² = (a + b)(a − b) to find 55² − 54².
  9. 9.Use a² − b² = (a + b)(a − b) to find 28² − 6².
  10. 10.Use a² − b² = (a + b)(a − b) to find 69² − 22².
  11. 11.Use (a + b)(a − b) = a² − b² to find 48 × 32.
  12. 12.Use (a + b)(a − b) = a² − b² to find 83 × 77.
  13. 13.Use a² − b² = (a + b)(a − b) to find 71² − 24².
  14. 14.Find the value of x² − 2xy + y² when x = 13 and y = 1.
  15. 15.Use a² − b² = (a + b)(a − b) to find 77² − 17².
  16. 16.Find the value of x² − y² when x = 10 and y = 9.
  17. 17.Use (a + b)(a − b) = a² − b² to find 25 × 15.
  18. 18.Use (a + b)² = a² + 2ab + b² to find 85².
  19. 19.Use (a − b)² = a² − 2ab + b² to find 15².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 16².
  21. 21.Find the value of x² + 2xy + y² when x = 5 and y = 1.
  22. 22.If a + b = 5 and ab = 4, what is a² + b²?
  23. 23.If a + b = 14 and ab = 48, what is a² + b²?
  24. 24.Use (a + b)² = a² + 2ab + b² to find 68².
  25. 25.If a − b = 3 and ab = 28, what is a² + b²?
  26. 26.Use (a + b)² = a² + 2ab + b² to find 31².
  27. 27.Use (a − b)² = a² − 2ab + b² to find 87².
  28. 28.Find the value of x² + 2xy + y² when x = 7 and y = 1.
  29. 29.Use a² − b² = (a + b)(a − b) to find 82² − 53².
  30. 30.Use (a + b)(a − b) = a² − b² to find 73 × 67.
  31. 31.Use (a + b)² = a² + 2ab + b² to find 29².
  32. 32.Use (a − b)² = a² − 2ab + b² to find 48².
  33. 33.Use (a − b)² = a² − 2ab + b² to find 96².
  34. 34.If a + b = 6 and ab = 5, what is a² + b²?
  35. 35.Use a² − b² = (a + b)(a − b) to find 87² − 61².
  36. 36.Use (a + b)² = a² + 2ab + b² to find 19².
  37. 37.Use (a + b)² = a² + 2ab + b² to find 95².
  38. 38.If a − b = 2 and ab = 3, what is a² + b²?
  39. 39.Use (a − b)² = a² − 2ab + b² to find 72².
  40. 40.Find the value of x² + 2xy + y² when x = 13 and y = 2.

Answer key

  1. 1444
  2. 8836
  3. 493
  4. 9991
  5. 25
  6. 3564
  7. 3721
  8. 109
  9. 748
  10. 4277
  11. 1536
  12. 6391
  13. 4465
  14. 144
  15. 5640
  16. 19
  17. 375
  18. 7225
  19. 225
  20. 256
  21. 36
  22. 17
  23. 100
  24. 4624
  25. 65
  26. 961
  27. 7569
  28. 64
  29. 3915
  30. 4891
  31. 841
  32. 2304
  33. 9216
  34. 26
  35. 3848
  36. 361
  37. 9025
  38. 10
  39. 5184
  40. 225

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