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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 576 · 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 53² − 49².
  2. 2.Use a² − b² = (a + b)(a − b) to find 98² − 26².
  3. 3.Use a² − b² = (a + b)(a − b) to find 55² − 5².
  4. 4.Use (a − b)² = a² − 2ab + b² to find 79².
  5. 5.Use (a + b)² = a² + 2ab + b² to find 15².
  6. 6.Find the value of x² − y² when x = 15 and y = 1.
  7. 7.Use a² − b² = (a + b)(a − b) to find 72² − 27².
  8. 8.Find the value of x² + 2xy + y² when x = 11 and y = 6.
  9. 9.Find the value of x² − y² when x = 3 and y = 1.
  10. 10.Find the value of x² + 2xy + y² when x = 10 and y = 4.
  11. 11.Find the value of x² − y² when x = 11 and y = 6.
  12. 12.Use (a + b)(a − b) = a² − b² to find 109 × 91.
  13. 13.Use a² − b² = (a + b)(a − b) to find 36² − 3².
  14. 14.Use a² − b² = (a + b)(a − b) to find 22² − 18².
  15. 15.Use (a + b)² = a² + 2ab + b² to find 85².
  16. 16.Use (a − b)² = a² − 2ab + b² to find 36².
  17. 17.Find the value of x² − 2xy + y² when x = 13 and y = 5.
  18. 18.Find the value of x² − 2xy + y² when x = 3 and y = 2.
  19. 19.If a + b = 8 and ab = 7, what is a² + b²?
  20. 20.Use (a + b)² = a² + 2ab + b² to find 19².
  21. 21.If a − b = 4 and ab = 21, what is a² + b²?
  22. 22.Use (a − b)² = a² − 2ab + b² to find 17².
  23. 23.Use a² − b² = (a + b)(a − b) to find 30² − 24².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 53².
  25. 25.Use a² − b² = (a + b)(a − b) to find 62² − 2².
  26. 26.If a + b = 12 and ab = 27, what is a² + b²?
  27. 27.Use (a + b)² = a² + 2ab + b² to find 31².
  28. 28.Use a² − b² = (a + b)(a − b) to find 54² − 37².
  29. 29.Use (a − b)² = a² − 2ab + b² to find 23².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 39².
  31. 31.Use (a + b)(a − b) = a² − b² to find 72 × 68.
  32. 32.Use a² − b² = (a + b)(a − b) to find 53² − 33².
  33. 33.Use (a + b)(a − b) = a² − b² to find 102 × 98.
  34. 34.Use (a − b)² = a² − 2ab + b² to find 22².
  35. 35.Use (a + b)(a − b) = a² − b² to find 32 × 28.
  36. 36.If a + b = 4 and ab = 3, what is a² + b²?
  37. 37.Find the value of x² − 2xy + y² when x = 13 and y = 11.
  38. 38.Use (a + b)(a − b) = a² − b² to find 54 × 46.
  39. 39.Find the value of x² + 2xy + y² when x = 11 and y = 7.
  40. 40.Use (a + b)² = a² + 2ab + b² to find 52².

Answer key

  1. 408
  2. 8928
  3. 3000
  4. 6241
  5. 225
  6. 224
  7. 4455
  8. 289
  9. 8
  10. 196
  11. 85
  12. 9919
  13. 1287
  14. 160
  15. 7225
  16. 1296
  17. 64
  18. 1
  19. 50
  20. 361
  21. 58
  22. 289
  23. 324
  24. 2809
  25. 3840
  26. 90
  27. 961
  28. 1547
  29. 529
  30. 1521
  31. 4896
  32. 1720
  33. 9996
  34. 484
  35. 896
  36. 10
  37. 4
  38. 2484
  39. 324
  40. 2704

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