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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 175 · 40 sums
TalentJR

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 = 12 and y = 2.
  2. 2.Use (a − b)² = a² − 2ab + b² to find 82².
  3. 3.Find the value of x² + 2xy + y² when x = 7 and y = 2.
  4. 4.Find the value of x² − 2xy + y² when x = 4 and y = 2.
  5. 5.Use a² − b² = (a + b)(a − b) to find 78² − 72².
  6. 6.Use a² − b² = (a + b)(a − b) to find 22² − 5².
  7. 7.Use (a + b)(a − b) = a² − b² to find 107 × 93.
  8. 8.Use (a + b)² = a² + 2ab + b² to find 91².
  9. 9.Use a² − b² = (a + b)(a − b) to find 49² − 12².
  10. 10.Use (a + b)(a − b) = a² − b² to find 58 × 42.
  11. 11.Find the value of x² − 2xy + y² when x = 15 and y = 4.
  12. 12.Use a² − b² = (a + b)(a − b) to find 50² − 46².
  13. 13.Use (a − b)² = a² − 2ab + b² to find 38².
  14. 14.Use (a + b)(a − b) = a² − b² to find 63 × 57.
  15. 15.Find the value of x² + 2xy + y² when x = 14 and y = 7.
  16. 16.Use (a + b)² = a² + 2ab + b² to find 48².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 37².
  18. 18.Use a² − b² = (a + b)(a − b) to find 57² − 48².
  19. 19.Use (a + b)(a − b) = a² − b² to find 104 × 96.
  20. 20.Use (a + b)(a − b) = a² − b² to find 55 × 45.
  21. 21.Use (a + b)² = a² + 2ab + b² to find 35².
  22. 22.Use a² − b² = (a + b)(a − b) to find 60² − 47².
  23. 23.Use a² − b² = (a + b)(a − b) to find 80² − 37².
  24. 24.Use a² − b² = (a + b)(a − b) to find 23² − 16².
  25. 25.Use (a − b)² = a² − 2ab + b² to find 23².
  26. 26.Use (a + b)² = a² + 2ab + b² to find 46².
  27. 27.Use a² − b² = (a + b)(a − b) to find 47² − 36².
  28. 28.Use a² − b² = (a + b)(a − b) to find 96² − 85².
  29. 29.Find the value of x² − y² when x = 4 and y = 1.
  30. 30.Use a² − b² = (a + b)(a − b) to find 30² − 5².
  31. 31.Use a² − b² = (a + b)(a − b) to find 79² − 75².
  32. 32.Find the value of x² − 2xy + y² when x = 6 and y = 4.
  33. 33.Find the value of x² + 2xy + y² when x = 5 and y = 4.
  34. 34.Use (a + b)² = a² + 2ab + b² to find 92².
  35. 35.Use (a + b)(a − b) = a² − b² to find 25 × 15.
  36. 36.If a − b = 3 and ab = 88, what is a² + b²?
  37. 37.Use a² − b² = (a + b)(a − b) to find 72² − 36².
  38. 38.Use (a + b)² = a² + 2ab + b² to find 41².
  39. 39.Use (a + b)(a − b) = a² − b² to find 91 × 89.
  40. 40.Use (a − b)² = a² − 2ab + b² to find 55².

Answer key

  1. 100
  2. 6724
  3. 81
  4. 4
  5. 900
  6. 459
  7. 9951
  8. 8281
  9. 2257
  10. 2436
  11. 121
  12. 384
  13. 1444
  14. 3591
  15. 441
  16. 2304
  17. 1369
  18. 945
  19. 9984
  20. 2475
  21. 1225
  22. 1391
  23. 5031
  24. 273
  25. 529
  26. 2116
  27. 913
  28. 1991
  29. 15
  30. 875
  31. 616
  32. 4
  33. 81
  34. 8464
  35. 375
  36. 185
  37. 3888
  38. 1681
  39. 8099
  40. 3025

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