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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 713 · 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 16².
  2. 2.If a − b = 2 and ab = 8, what is a² + b²?
  3. 3.Find the value of x² − y² when x = 11 and y = 6.
  4. 4.Use (a + b)² = a² + 2ab + b² to find 43².
  5. 5.If a − b = 1 and ab = 72, what is a² + b²?
  6. 6.Use (a − b)² = a² − 2ab + b² to find 86².
  7. 7.Use a² − b² = (a + b)(a − b) to find 40² − 34².
  8. 8.Find the value of x² + 2xy + y² when x = 12 and y = 11.
  9. 9.Find the value of x² + 2xy + y² when x = 6 and y = 3.
  10. 10.Use (a + b)(a − b) = a² − b² to find 49 × 31.
  11. 11.Use (a − b)² = a² − 2ab + b² to find 87².
  12. 12.Use (a + b)² = a² + 2ab + b² to find 63².
  13. 13.Find the value of x² − y² when x = 4 and y = 1.
  14. 14.Use a² − b² = (a + b)(a − b) to find 57² − 52².
  15. 15.If a − b = 1 and ab = 6, what is a² + b²?
  16. 16.Use (a + b)² = a² + 2ab + b² to find 92².
  17. 17.Find the value of x² − y² when x = 10 and y = 1.
  18. 18.Use a² − b² = (a + b)(a − b) to find 40² − 39².
  19. 19.Use a² − b² = (a + b)(a − b) to find 87² − 36².
  20. 20.Use (a + b)² = a² + 2ab + b² to find 22².
  21. 21.Use (a − b)² = a² − 2ab + b² to find 75².
  22. 22.Use (a + b)(a − b) = a² − b² to find 95 × 85.
  23. 23.Use a² − b² = (a + b)(a − b) to find 39² − 6².
  24. 24.Use (a − b)² = a² − 2ab + b² to find 44².
  25. 25.Use (a + b)² = a² + 2ab + b² to find 53².
  26. 26.Use (a + b)² = a² + 2ab + b² to find 66².
  27. 27.Use a² − b² = (a + b)(a − b) to find 71² − 33².
  28. 28.Use a² − b² = (a + b)(a − b) to find 70² − 21².
  29. 29.Use (a + b)(a − b) = a² − b² to find 38 × 22.
  30. 30.Use (a − b)² = a² − 2ab + b² to find 26².
  31. 31.Use (a + b)(a − b) = a² − b² to find 37 × 23.
  32. 32.Use (a + b)² = a² + 2ab + b² to find 91².
  33. 33.If a + b = 19 and ab = 90, what is a² + b²?
  34. 34.Use (a + b)² = a² + 2ab + b² to find 25².
  35. 35.Find the value of x² + 2xy + y² when x = 11 and y = 1.
  36. 36.Use (a − b)² = a² − 2ab + b² to find 89².
  37. 37.Find the value of x² − 2xy + y² when x = 6 and y = 2.
  38. 38.Use (a − b)² = a² − 2ab + b² to find 12².
  39. 39.Use a² − b² = (a + b)(a − b) to find 90² − 46².
  40. 40.Use (a − b)² = a² − 2ab + b² to find 35².

Answer key

  1. 256
  2. 20
  3. 85
  4. 1849
  5. 145
  6. 7396
  7. 444
  8. 529
  9. 81
  10. 1519
  11. 7569
  12. 3969
  13. 15
  14. 545
  15. 13
  16. 8464
  17. 99
  18. 79
  19. 6273
  20. 484
  21. 5625
  22. 8075
  23. 1485
  24. 1936
  25. 2809
  26. 4356
  27. 3952
  28. 4459
  29. 836
  30. 676
  31. 851
  32. 8281
  33. 181
  34. 625
  35. 144
  36. 7921
  37. 16
  38. 144
  39. 5984
  40. 1225

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