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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 363 · 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 55² − 32².
  2. 2.Use a² − b² = (a + b)(a − b) to find 37² − 30².
  3. 3.Use (a + b)(a − b) = a² − b² to find 96 × 84.
  4. 4.Use (a + b)(a − b) = a² − b² to find 67 × 53.
  5. 5.Use (a − b)² = a² − 2ab + b² to find 78².
  6. 6.Use a² − b² = (a + b)(a − b) to find 62² − 2².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 36².
  8. 8.Use (a − b)² = a² − 2ab + b² to find 89².
  9. 9.If a + b = 18 and ab = 77, what is a² + b²?
  10. 10.If a − b = 1 and ab = 6, what is a² + b²?
  11. 11.Use (a + b)² = a² + 2ab + b² to find 85².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 45².
  13. 13.Use (a + b)² = a² + 2ab + b² to find 91².
  14. 14.Use (a − b)² = a² − 2ab + b² to find 46².
  15. 15.Find the value of x² − y² when x = 4 and y = 3.
  16. 16.Use a² − b² = (a + b)(a − b) to find 36² − 22².
  17. 17.Use (a + b)(a − b) = a² − b² to find 23 × 17.
  18. 18.Use a² − b² = (a + b)(a − b) to find 90² − 46².
  19. 19.Use a² − b² = (a + b)(a − b) to find 91² − 36².
  20. 20.Use a² − b² = (a + b)(a − b) to find 38² − 29².
  21. 21.Use (a + b)(a − b) = a² − b² to find 32 × 28.
  22. 22.Use (a + b)² = a² + 2ab + b² to find 86².
  23. 23.Find the value of x² − y² when x = 12 and y = 3.
  24. 24.Use (a − b)² = a² − 2ab + b² to find 54².
  25. 25.Use (a − b)² = a² − 2ab + b² to find 76².
  26. 26.Use (a − b)² = a² − 2ab + b² to find 37².
  27. 27.If a − b = 6 and ab = 16, what is a² + b²?
  28. 28.Find the value of x² − y² when x = 10 and y = 8.
  29. 29.Find the value of x² − y² when x = 11 and y = 9.
  30. 30.Find the value of x² − 2xy + y² when x = 5 and y = 3.
  31. 31.Use (a − b)² = a² − 2ab + b² to find 52².
  32. 32.Use a² − b² = (a + b)(a − b) to find 27² − 17².
  33. 33.If a − b = 2 and ab = 80, what is a² + b²?
  34. 34.Use (a − b)² = a² − 2ab + b² to find 44².
  35. 35.Find the value of x² − y² when x = 7 and y = 6.
  36. 36.Find the value of x² + 2xy + y² when x = 5 and y = 3.
  37. 37.Use a² − b² = (a + b)(a − b) to find 28² − 2².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 87².
  39. 39.If a + b = 11 and ab = 28, what is a² + b²?
  40. 40.Use (a + b)(a − b) = a² − b² to find 31 × 29.

Answer key

  1. 2001
  2. 469
  3. 8064
  4. 3551
  5. 6084
  6. 3840
  7. 1296
  8. 7921
  9. 170
  10. 13
  11. 7225
  12. 2025
  13. 8281
  14. 2116
  15. 7
  16. 812
  17. 391
  18. 5984
  19. 6985
  20. 603
  21. 896
  22. 7396
  23. 135
  24. 2916
  25. 5776
  26. 1369
  27. 68
  28. 36
  29. 40
  30. 4
  31. 2704
  32. 440
  33. 164
  34. 1936
  35. 13
  36. 64
  37. 780
  38. 7569
  39. 65
  40. 899

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