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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 392 · 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 (a + b)² = a² + 2ab + b² to find 72².
  3. 3.Find the value of x² − 2xy + y² when x = 7 and y = 1.
  4. 4.Use (a − b)² = a² − 2ab + b² to find 37².
  5. 5.Use (a + b)² = a² + 2ab + b² to find 61².
  6. 6.Use (a + b)² = a² + 2ab + b² to find 16².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 22².
  8. 8.If a − b = 1 and ab = 132, what is a² + b²?
  9. 9.If a + b = 9 and ab = 20, what is a² + b²?
  10. 10.Use (a − b)² = a² − 2ab + b² to find 19².
  11. 11.Find the value of x² + 2xy + y² when x = 5 and y = 4.
  12. 12.Use a² − b² = (a + b)(a − b) to find 20² − 12².
  13. 13.If a + b = 15 and ab = 44, what is a² + b²?
  14. 14.Use (a + b)(a − b) = a² − b² to find 67 × 53.
  15. 15.Use (a − b)² = a² − 2ab + b² to find 31².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 102².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 12².
  18. 18.Find the value of x² − 2xy + y² when x = 15 and y = 5.
  19. 19.Use a² − b² = (a + b)(a − b) to find 64² − 33².
  20. 20.If a − b = 3 and ab = 4, what is a² + b²?
  21. 21.Use a² − b² = (a + b)(a − b) to find 37² − 34².
  22. 22.Use a² − b² = (a + b)(a − b) to find 53² − 9².
  23. 23.Use (a + b)(a − b) = a² − b² to find 75 × 65.
  24. 24.Use (a + b)² = a² + 2ab + b² to find 105².
  25. 25.Use (a − b)² = a² − 2ab + b² to find 44².
  26. 26.Use (a + b)(a − b) = a² − b² to find 105 × 95.
  27. 27.Use (a − b)² = a² − 2ab + b² to find 45².
  28. 28.Use a² − b² = (a + b)(a − b) to find 32² − 8².
  29. 29.Use a² − b² = (a + b)(a − b) to find 84² − 65².
  30. 30.If a + b = 15 and ab = 50, what is a² + b²?
  31. 31.Use (a + b)² = a² + 2ab + b² to find 107².
  32. 32.Use (a − b)² = a² − 2ab + b² to find 36².
  33. 33.If a − b = 1 and ab = 2, what is a² + b²?
  34. 34.Use (a − b)² = a² − 2ab + b² to find 83².
  35. 35.Use (a + b)(a − b) = a² − b² to find 77 × 63.
  36. 36.Use (a − b)² = a² − 2ab + b² to find 73².
  37. 37.Find the value of x² + 2xy + y² when x = 7 and y = 6.
  38. 38.Use (a + b)(a − b) = a² − b² to find 42 × 38.
  39. 39.Use (a − b)² = a² − 2ab + b² to find 29².
  40. 40.Use (a + b)² = a² + 2ab + b² to find 76².

Answer key

  1. 7744
  2. 5184
  3. 36
  4. 1369
  5. 3721
  6. 256
  7. 484
  8. 265
  9. 41
  10. 361
  11. 81
  12. 256
  13. 137
  14. 3551
  15. 961
  16. 10404
  17. 144
  18. 100
  19. 3007
  20. 17
  21. 213
  22. 2728
  23. 4875
  24. 11025
  25. 1936
  26. 9975
  27. 2025
  28. 960
  29. 2831
  30. 125
  31. 11449
  32. 1296
  33. 5
  34. 6889
  35. 4851
  36. 5329
  37. 169
  38. 1596
  39. 841
  40. 5776

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