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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 714 · 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 87².
  2. 2.Use (a − b)² = a² − 2ab + b² to find 33².
  3. 3.Use a² − b² = (a + b)(a − b) to find 24² − 23².
  4. 4.If a − b = 8 and ab = 20, what is a² + b²?
  5. 5.Use (a + b)(a − b) = a² − b² to find 106 × 94.
  6. 6.Use (a − b)² = a² − 2ab + b² to find 69².
  7. 7.Use a² − b² = (a + b)(a − b) to find 97² − 96².
  8. 8.Use (a + b)² = a² + 2ab + b² to find 54².
  9. 9.Use (a − b)² = a² − 2ab + b² to find 11².
  10. 10.Use a² − b² = (a + b)(a − b) to find 26² − 2².
  11. 11.Find the value of x² + 2xy + y² when x = 5 and y = 4.
  12. 12.Use (a − b)² = a² − 2ab + b² to find 42².
  13. 13.Use a² − b² = (a + b)(a − b) to find 63² − 1².
  14. 14.Find the value of x² − y² when x = 3 and y = 1.
  15. 15.Find the value of x² − y² when x = 9 and y = 3.
  16. 16.Use (a + b)(a − b) = a² − b² to find 65 × 55.
  17. 17.Use (a + b)² = a² + 2ab + b² to find 73².
  18. 18.If a − b = 5 and ab = 50, what is a² + b²?
  19. 19.Use (a + b)² = a² + 2ab + b² to find 29².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 99².
  21. 21.If a + b = 3 and ab = 2, what is a² + b²?
  22. 22.Use (a − b)² = a² − 2ab + b² to find 82².
  23. 23.Find the value of x² − 2xy + y² when x = 9 and y = 7.
  24. 24.Use (a + b)² = a² + 2ab + b² to find 79².
  25. 25.Use a² − b² = (a + b)(a − b) to find 85² − 65².
  26. 26.Find the value of x² + 2xy + y² when x = 6 and y = 1.
  27. 27.Use a² − b² = (a + b)(a − b) to find 59² − 11².
  28. 28.Use a² − b² = (a + b)(a − b) to find 25² − 22².
  29. 29.Use (a − b)² = a² − 2ab + b² to find 89².
  30. 30.Use (a + b)(a − b) = a² − b² to find 85 × 75.
  31. 31.Use (a − b)² = a² − 2ab + b² to find 44².
  32. 32.Use (a + b)(a − b) = a² − b² to find 83 × 77.
  33. 33.Use a² − b² = (a + b)(a − b) to find 64² − 11².
  34. 34.Use a² − b² = (a + b)(a − b) to find 63² − 43².
  35. 35.Use (a + b)² = a² + 2ab + b² to find 86².
  36. 36.Use (a + b)² = a² + 2ab + b² to find 55².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 13².
  38. 38.Find the value of x² − 2xy + y² when x = 7 and y = 1.
  39. 39.Use (a + b)² = a² + 2ab + b² to find 61².
  40. 40.Use (a + b)² = a² + 2ab + b² to find 66².

Answer key

  1. 7569
  2. 1089
  3. 47
  4. 104
  5. 9964
  6. 4761
  7. 193
  8. 2916
  9. 121
  10. 672
  11. 81
  12. 1764
  13. 3968
  14. 8
  15. 72
  16. 3575
  17. 5329
  18. 125
  19. 841
  20. 9801
  21. 5
  22. 6724
  23. 4
  24. 6241
  25. 3000
  26. 49
  27. 3360
  28. 141
  29. 7921
  30. 6375
  31. 1936
  32. 6391
  33. 3975
  34. 2120
  35. 7396
  36. 3025
  37. 169
  38. 36
  39. 3721
  40. 4356

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