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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 242 · 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 88².
  2. 2.Use a² − b² = (a + b)(a − b) to find 75² − 58².
  3. 3.If a + b = 11 and ab = 18, what is a² + b²?
  4. 4.Find the value of x² − y² when x = 7 and y = 4.
  5. 5.Use (a + b)(a − b) = a² − b² to find 92 × 88.
  6. 6.If a − b = 2 and ab = 8, what is a² + b²?
  7. 7.If a + b = 15 and ab = 56, what is a² + b²?
  8. 8.Use a² − b² = (a + b)(a − b) to find 38² − 10².
  9. 9.Use a² − b² = (a + b)(a − b) to find 95² − 65².
  10. 10.Use (a + b)(a − b) = a² − b² to find 71 × 69.
  11. 11.Use (a + b)(a − b) = a² − b² to find 44 × 36.
  12. 12.Use (a + b)(a − b) = a² − b² to find 68 × 52.
  13. 13.Use (a − b)² = a² − 2ab + b² to find 41².
  14. 14.Use (a + b)² = a² + 2ab + b² to find 54².
  15. 15.Find the value of x² − y² when x = 4 and y = 3.
  16. 16.Find the value of x² − y² when x = 5 and y = 4.
  17. 17.Use (a − b)² = a² − 2ab + b² to find 54².
  18. 18.Use (a + b)² = a² + 2ab + b² to find 56².
  19. 19.Use (a − b)² = a² − 2ab + b² to find 38².
  20. 20.Use (a + b)² = a² + 2ab + b² to find 101².
  21. 21.If a − b = 1 and ab = 2, what is a² + b²?
  22. 22.Use (a + b)² = a² + 2ab + b² to find 11².
  23. 23.Find the value of x² − 2xy + y² when x = 11 and y = 9.
  24. 24.Use a² − b² = (a + b)(a − b) to find 92² − 17².
  25. 25.Find the value of x² − 2xy + y² when x = 14 and y = 3.
  26. 26.Use (a − b)² = a² − 2ab + b² to find 81².
  27. 27.Use (a + b)² = a² + 2ab + b² to find 103².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 49².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 81².
  30. 30.Find the value of x² − 2xy + y² when x = 3 and y = 2.
  31. 31.Use a² − b² = (a + b)(a − b) to find 98² − 68².
  32. 32.Use (a + b)(a − b) = a² − b² to find 58 × 42.
  33. 33.Find the value of x² − 2xy + y² when x = 14 and y = 11.
  34. 34.Use (a + b)(a − b) = a² − b² to find 28 × 12.
  35. 35.Use (a + b)² = a² + 2ab + b² to find 26².
  36. 36.If a − b = 2 and ab = 15, what is a² + b²?
  37. 37.Use (a − b)² = a² − 2ab + b² to find 36².
  38. 38.If a − b = 3 and ab = 18, what is a² + b²?
  39. 39.Use a² − b² = (a + b)(a − b) to find 77² − 66².
  40. 40.Use a² − b² = (a + b)(a − b) to find 95² − 25².

Answer key

  1. 7744
  2. 2261
  3. 85
  4. 33
  5. 8096
  6. 20
  7. 113
  8. 1344
  9. 4800
  10. 4899
  11. 1584
  12. 3536
  13. 1681
  14. 2916
  15. 7
  16. 9
  17. 2916
  18. 3136
  19. 1444
  20. 10201
  21. 5
  22. 121
  23. 4
  24. 8175
  25. 121
  26. 6561
  27. 10609
  28. 2401
  29. 6561
  30. 1
  31. 4980
  32. 2436
  33. 9
  34. 336
  35. 676
  36. 34
  37. 1296
  38. 45
  39. 1573
  40. 8400

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