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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 100 · 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)(a − b) = a² − b² to find 29 × 11.
  2. 2.Use (a + b)(a − b) = a² − b² to find 87 × 73.
  3. 3.Use a² − b² = (a + b)(a − b) to find 68² − 33².
  4. 4.Find the value of x² − 2xy + y² when x = 9 and y = 7.
  5. 5.Use (a + b)² = a² + 2ab + b² to find 53².
  6. 6.Use (a + b)(a − b) = a² − b² to find 93 × 87.
  7. 7.If a − b = 1 and ab = 56, what is a² + b²?
  8. 8.Use (a − b)² = a² − 2ab + b² to find 37².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 88².
  10. 10.If a + b = 3 and ab = 2, what is a² + b²?
  11. 11.Use a² − b² = (a + b)(a − b) to find 59² − 34².
  12. 12.Use (a + b)² = a² + 2ab + b² to find 74².
  13. 13.Find the value of x² + 2xy + y² when x = 3 and y = 1.
  14. 14.If a − b = 4 and ab = 32, what is a² + b²?
  15. 15.If a − b = 1 and ab = 110, what is a² + b²?
  16. 16.Use (a + b)² = a² + 2ab + b² to find 82².
  17. 17.Use a² − b² = (a + b)(a − b) to find 77² − 62².
  18. 18.Use (a + b)² = a² + 2ab + b² to find 14².
  19. 19.Find the value of x² − 2xy + y² when x = 4 and y = 2.
  20. 20.Use (a − b)² = a² − 2ab + b² to find 85².
  21. 21.Use (a − b)² = a² − 2ab + b² to find 95².
  22. 22.Use (a − b)² = a² − 2ab + b² to find 33².
  23. 23.Use (a − b)² = a² − 2ab + b² to find 88².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 43².
  25. 25.Find the value of x² + 2xy + y² when x = 11 and y = 1.
  26. 26.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  27. 27.Use (a − b)² = a² − 2ab + b² to find 39².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 55².
  29. 29.Use a² − b² = (a + b)(a − b) to find 91² − 54².
  30. 30.Use (a − b)² = a² − 2ab + b² to find 58².
  31. 31.Find the value of x² − 2xy + y² when x = 9 and y = 2.
  32. 32.Use (a + b)(a − b) = a² − b² to find 37 × 23.
  33. 33.Use a² − b² = (a + b)(a − b) to find 65² − 13².
  34. 34.Find the value of x² − y² when x = 9 and y = 2.
  35. 35.Use (a + b)² = a² + 2ab + b² to find 57².
  36. 36.Use (a + b)² = a² + 2ab + b² to find 34².
  37. 37.Use a² − b² = (a + b)(a − b) to find 31² − 21².
  38. 38.Use (a + b)² = a² + 2ab + b² to find 54².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 12².
  40. 40.Find the value of x² + 2xy + y² when x = 10 and y = 6.

Answer key

  1. 319
  2. 6351
  3. 3535
  4. 4
  5. 2809
  6. 8091
  7. 113
  8. 1369
  9. 7744
  10. 5
  11. 2325
  12. 5476
  13. 16
  14. 80
  15. 221
  16. 6724
  17. 2085
  18. 196
  19. 4
  20. 7225
  21. 9025
  22. 1089
  23. 7744
  24. 1849
  25. 144
  26. 1591
  27. 1521
  28. 3025
  29. 5365
  30. 3364
  31. 49
  32. 851
  33. 4056
  34. 77
  35. 3249
  36. 1156
  37. 520
  38. 2916
  39. 144
  40. 256

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