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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 41 · 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 a² − b² = (a + b)(a − b) to find 42² − 35².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 49².
  3. 3.Find the value of x² − y² when x = 4 and y = 1.
  4. 4.Use (a − b)² = a² − 2ab + b² to find 43².
  5. 5.Use (a + b)(a − b) = a² − b² to find 103 × 97.
  6. 6.Use (a − b)² = a² − 2ab + b² to find 54².
  7. 7.Find the value of x² + 2xy + y² when x = 9 and y = 3.
  8. 8.Use a² − b² = (a + b)(a − b) to find 35² − 32².
  9. 9.Find the value of x² + 2xy + y² when x = 13 and y = 1.
  10. 10.Use (a − b)² = a² − 2ab + b² to find 32².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 98².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 84².
  13. 13.If a + b = 5 and ab = 4, what is a² + b²?
  14. 14.Find the value of x² + 2xy + y² when x = 15 and y = 12.
  15. 15.If a + b = 3 and ab = 2, what is a² + b²?
  16. 16.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  17. 17.Use (a + b)(a − b) = a² − b² to find 95 × 85.
  18. 18.If a − b = 3 and ab = 4, what is a² + b²?
  19. 19.Use (a − b)² = a² − 2ab + b² to find 94².
  20. 20.If a + b = 4 and ab = 3, what is a² + b²?
  21. 21.If a + b = 12 and ab = 35, what is a² + b²?
  22. 22.If a − b = 3 and ab = 10, what is a² + b²?
  23. 23.Use (a − b)² = a² − 2ab + b² to find 77².
  24. 24.Use (a − b)² = a² − 2ab + b² to find 85².
  25. 25.Use (a + b)(a − b) = a² − b² to find 52 × 48.
  26. 26.Use (a + b)(a − b) = a² − b² to find 33 × 27.
  27. 27.Use (a + b)(a − b) = a² − b² to find 24 × 16.
  28. 28.Use (a − b)² = a² − 2ab + b² to find 25².
  29. 29.Use a² − b² = (a + b)(a − b) to find 38² − 4².
  30. 30.Use (a − b)² = a² − 2ab + b² to find 21².
  31. 31.Use (a + b)² = a² + 2ab + b² to find 52².
  32. 32.Use (a + b)² = a² + 2ab + b² to find 38².
  33. 33.Find the value of x² − y² when x = 5 and y = 1.
  34. 34.Use a² − b² = (a + b)(a − b) to find 53² − 36².
  35. 35.If a + b = 15 and ab = 50, what is a² + b²?
  36. 36.Use (a − b)² = a² − 2ab + b² to find 26².
  37. 37.Use a² − b² = (a + b)(a − b) to find 23² − 22².
  38. 38.Find the value of x² − y² when x = 6 and y = 5.
  39. 39.Find the value of x² + 2xy + y² when x = 6 and y = 4.
  40. 40.Use (a + b)² = a² + 2ab + b² to find 92².

Answer key

  1. 539
  2. 2401
  3. 15
  4. 1849
  5. 9991
  6. 2916
  7. 144
  8. 201
  9. 196
  10. 1024
  11. 9604
  12. 7056
  13. 17
  14. 729
  15. 5
  16. 1591
  17. 8075
  18. 17
  19. 8836
  20. 10
  21. 74
  22. 29
  23. 5929
  24. 7225
  25. 2496
  26. 891
  27. 384
  28. 625
  29. 1428
  30. 441
  31. 2704
  32. 1444
  33. 24
  34. 1513
  35. 125
  36. 676
  37. 45
  38. 11
  39. 100
  40. 8464

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