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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 993 · 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 = 15 and y = 7.
  2. 2.If a − b = 5 and ab = 24, what is a² + b²?
  3. 3.Use a² − b² = (a + b)(a − b) to find 84² − 57².
  4. 4.Use (a − b)² = a² − 2ab + b² to find 95².
  5. 5.Use (a + b)² = a² + 2ab + b² to find 37².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 48².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 103².
  8. 8.Use a² − b² = (a + b)(a − b) to find 56² − 37².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 102².
  10. 10.If a − b = 1 and ab = 110, what is a² + b²?
  11. 11.Find the value of x² − y² when x = 13 and y = 3.
  12. 12.If a + b = 16 and ab = 55, what is a² + b²?
  13. 13.Use (a − b)² = a² − 2ab + b² to find 35².
  14. 14.Use (a + b)(a − b) = a² − b² to find 79 × 61.
  15. 15.Use (a + b)(a − b) = a² − b² to find 24 × 16.
  16. 16.Use (a − b)² = a² − 2ab + b² to find 93².
  17. 17.Find the value of x² − y² when x = 3 and y = 2.
  18. 18.Use (a + b)² = a² + 2ab + b² to find 89².
  19. 19.Use (a − b)² = a² − 2ab + b² to find 38².
  20. 20.If a + b = 15 and ab = 50, what is a² + b²?
  21. 21.If a − b = 6 and ab = 27, what is a² + b²?
  22. 22.Find the value of x² − 2xy + y² when x = 9 and y = 5.
  23. 23.If a − b = 4 and ab = 60, what is a² + b²?
  24. 24.Find the value of x² + 2xy + y² when x = 5 and y = 1.
  25. 25.Use a² − b² = (a + b)(a − b) to find 25² − 23².
  26. 26.Use (a + b)(a − b) = a² − b² to find 68 × 52.
  27. 27.Use (a + b)² = a² + 2ab + b² to find 73².
  28. 28.Use (a − b)² = a² − 2ab + b² to find 31².
  29. 29.If a + b = 17 and ab = 66, what is a² + b²?
  30. 30.Find the value of x² − 2xy + y² when x = 5 and y = 1.
  31. 31.Use (a + b)² = a² + 2ab + b² to find 51².
  32. 32.If a + b = 5 and ab = 4, what is a² + b²?
  33. 33.Use (a + b)(a − b) = a² − b² to find 94 × 86.
  34. 34.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  35. 35.If a − b = 3 and ab = 28, what is a² + b²?
  36. 36.Use (a + b)² = a² + 2ab + b² to find 34².
  37. 37.If a + b = 12 and ab = 35, what is a² + b²?
  38. 38.Use (a − b)² = a² − 2ab + b² to find 87².
  39. 39.Use (a − b)² = a² − 2ab + b² to find 34².
  40. 40.Use a² − b² = (a + b)(a − b) to find 92² − 85².

Answer key

  1. 64
  2. 73
  3. 3807
  4. 9025
  5. 1369
  6. 2304
  7. 10609
  8. 1767
  9. 10404
  10. 221
  11. 160
  12. 146
  13. 1225
  14. 4819
  15. 384
  16. 8649
  17. 5
  18. 7921
  19. 1444
  20. 125
  21. 90
  22. 16
  23. 136
  24. 36
  25. 96
  26. 3536
  27. 5329
  28. 961
  29. 157
  30. 16
  31. 2601
  32. 17
  33. 8084
  34. 899
  35. 65
  36. 1156
  37. 74
  38. 7569
  39. 1156
  40. 1239

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