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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 233 · 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 83².
  2. 2.Find the value of x² − y² when x = 15 and y = 7.
  3. 3.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  4. 4.Use (a + b)(a − b) = a² − b² to find 96 × 84.
  5. 5.Use (a + b)² = a² + 2ab + b² to find 22².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 37².
  7. 7.Use a² − b² = (a + b)(a − b) to find 76² − 39².
  8. 8.Use (a − b)² = a² − 2ab + b² to find 52².
  9. 9.Find the value of x² + 2xy + y² when x = 13 and y = 5.
  10. 10.Use (a − b)² = a² − 2ab + b² to find 22².
  11. 11.Use (a + b)² = a² + 2ab + b² to find 15².
  12. 12.If a + b = 11 and ab = 28, what is a² + b²?
  13. 13.Use (a + b)(a − b) = a² − b² to find 22 × 18.
  14. 14.Find the value of x² − y² when x = 4 and y = 2.
  15. 15.If a + b = 13 and ab = 22, what is a² + b²?
  16. 16.If a + b = 8 and ab = 7, what is a² + b²?
  17. 17.Use a² − b² = (a + b)(a − b) to find 30² − 2².
  18. 18.If a − b = 8 and ab = 33, what is a² + b²?
  19. 19.Use (a + b)(a − b) = a² − b² to find 42 × 38.
  20. 20.Use (a + b)(a − b) = a² − b² to find 82 × 78.
  21. 21.Use (a − b)² = a² − 2ab + b² to find 16².
  22. 22.Use (a − b)² = a² − 2ab + b² to find 19².
  23. 23.Use (a + b)² = a² + 2ab + b² to find 47².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 92².
  25. 25.If a + b = 15 and ab = 56, what is a² + b²?
  26. 26.If a + b = 15 and ab = 50, what is a² + b²?
  27. 27.Find the value of x² − y² when x = 9 and y = 7.
  28. 28.If a − b = 3 and ab = 28, what is a² + b²?
  29. 29.Use (a − b)² = a² − 2ab + b² to find 62².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 107².
  31. 31.Use (a − b)² = a² − 2ab + b² to find 77².
  32. 32.Use (a + b)(a − b) = a² − b² to find 71 × 69.
  33. 33.Use (a − b)² = a² − 2ab + b² to find 47².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 108².
  35. 35.Use (a + b)(a − b) = a² − b² to find 29 × 11.
  36. 36.Use a² − b² = (a + b)(a − b) to find 43² − 26².
  37. 37.Use (a + b)² = a² + 2ab + b² to find 69².
  38. 38.If a + b = 5 and ab = 4, what is a² + b²?
  39. 39.Use (a − b)² = a² − 2ab + b² to find 83².
  40. 40.Find the value of x² − 2xy + y² when x = 4 and y = 1.

Answer key

  1. 6889
  2. 176
  3. 1591
  4. 8064
  5. 484
  6. 1369
  7. 4255
  8. 2704
  9. 324
  10. 484
  11. 225
  12. 65
  13. 396
  14. 12
  15. 125
  16. 50
  17. 896
  18. 130
  19. 1596
  20. 6396
  21. 256
  22. 361
  23. 2209
  24. 8464
  25. 113
  26. 125
  27. 32
  28. 65
  29. 3844
  30. 11449
  31. 5929
  32. 4899
  33. 2209
  34. 11664
  35. 319
  36. 1173
  37. 4761
  38. 17
  39. 6889
  40. 9

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