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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 844 · 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.Find the value of x² − 2xy + y² when x = 11 and y = 10.
  2. 2.Use (a + b)² = a² + 2ab + b² to find 21².
  3. 3.Use (a + b)² = a² + 2ab + b² to find 89².
  4. 4.If a − b = 1 and ab = 2, what is a² + b²?
  5. 5.Use (a + b)² = a² + 2ab + b² to find 35².
  6. 6.Use (a + b)² = a² + 2ab + b² to find 91².
  7. 7.Use a² − b² = (a + b)(a − b) to find 61² − 21².
  8. 8.Use a² − b² = (a + b)(a − b) to find 36² − 12².
  9. 9.If a + b = 20 and ab = 96, what is a² + b²?
  10. 10.Use (a − b)² = a² − 2ab + b² to find 38².
  11. 11.If a + b = 16 and ab = 55, what is a² + b²?
  12. 12.Find the value of x² − y² when x = 7 and y = 3.
  13. 13.Use a² − b² = (a + b)(a − b) to find 33² − 29².
  14. 14.Use (a + b)(a − b) = a² − b² to find 44 × 36.
  15. 15.If a + b = 8 and ab = 7, what is a² + b²?
  16. 16.Use (a + b)² = a² + 2ab + b² to find 11².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 66².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 72².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 22².
  20. 20.Use (a + b)(a − b) = a² − b² to find 71 × 69.
  21. 21.Use a² − b² = (a + b)(a − b) to find 84² − 66².
  22. 22.Use (a − b)² = a² − 2ab + b² to find 39².
  23. 23.Use a² − b² = (a + b)(a − b) to find 39² − 13².
  24. 24.Use (a − b)² = a² − 2ab + b² to find 64².
  25. 25.Use a² − b² = (a + b)(a − b) to find 57² − 28².
  26. 26.Use (a + b)² = a² + 2ab + b² to find 98².
  27. 27.Find the value of x² + 2xy + y² when x = 14 and y = 3.
  28. 28.Use (a − b)² = a² − 2ab + b² to find 83².
  29. 29.Use a² − b² = (a + b)(a − b) to find 78² − 72².
  30. 30.Use (a + b)(a − b) = a² − b² to find 49 × 31.
  31. 31.Use (a + b)² = a² + 2ab + b² to find 26².
  32. 32.Use (a + b)(a − b) = a² − b² to find 42 × 38.
  33. 33.Use (a + b)(a − b) = a² − b² to find 93 × 87.
  34. 34.If a − b = 3 and ab = 10, what is a² + b²?
  35. 35.Use a² − b² = (a + b)(a − b) to find 26² − 11².
  36. 36.Use (a + b)² = a² + 2ab + b² to find 17².
  37. 37.Find the value of x² + 2xy + y² when x = 6 and y = 3.
  38. 38.Use (a − b)² = a² − 2ab + b² to find 93².
  39. 39.Use a² − b² = (a + b)(a − b) to find 49² − 9².
  40. 40.Use (a − b)² = a² − 2ab + b² to find 97².

Answer key

  1. 1
  2. 441
  3. 7921
  4. 5
  5. 1225
  6. 8281
  7. 3280
  8. 1152
  9. 208
  10. 1444
  11. 146
  12. 40
  13. 248
  14. 1584
  15. 50
  16. 121
  17. 4356
  18. 5184
  19. 484
  20. 4899
  21. 2700
  22. 1521
  23. 1352
  24. 4096
  25. 2465
  26. 9604
  27. 289
  28. 6889
  29. 900
  30. 1519
  31. 676
  32. 1596
  33. 8091
  34. 29
  35. 555
  36. 289
  37. 81
  38. 8649
  39. 2320
  40. 9409

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