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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 616 · 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 = 6 and y = 5.
  2. 2.Use (a + b)² = a² + 2ab + b² to find 66².
  3. 3.Find the value of x² + 2xy + y² when x = 9 and y = 3.
  4. 4.If a − b = 2 and ab = 3, what is a² + b²?
  5. 5.Use (a − b)² = a² − 2ab + b² to find 27².
  6. 6.If a + b = 4 and ab = 3, what is a² + b²?
  7. 7.If a − b = 1 and ab = 2, what is a² + b²?
  8. 8.Find the value of x² − y² when x = 14 and y = 7.
  9. 9.Find the value of x² − y² when x = 13 and y = 2.
  10. 10.Use a² − b² = (a + b)(a − b) to find 61² − 44².
  11. 11.Use (a + b)(a − b) = a² − b² to find 71 × 69.
  12. 12.Use (a − b)² = a² − 2ab + b² to find 61².
  13. 13.Use (a − b)² = a² − 2ab + b² to find 32².
  14. 14.Use (a − b)² = a² − 2ab + b² to find 57².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 94².
  16. 16.Use (a + b)(a − b) = a² − b² to find 41 × 39.
  17. 17.Use (a + b)² = a² + 2ab + b² to find 33².
  18. 18.Use (a + b)² = a² + 2ab + b² to find 71².
  19. 19.Use (a − b)² = a² − 2ab + b² to find 69².
  20. 20.Use (a + b)² = a² + 2ab + b² to find 96².
  21. 21.Find the value of x² + 2xy + y² when x = 6 and y = 3.
  22. 22.Use (a + b)² = a² + 2ab + b² to find 16².
  23. 23.Use (a − b)² = a² − 2ab + b² to find 77².
  24. 24.Use a² − b² = (a + b)(a − b) to find 29² − 24².
  25. 25.Use (a + b)² = a² + 2ab + b² to find 81².
  26. 26.Use a² − b² = (a + b)(a − b) to find 82² − 22².
  27. 27.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  28. 28.Use (a + b)² = a² + 2ab + b² to find 22².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 18².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 59².
  31. 31.If a + b = 10 and ab = 21, what is a² + b²?
  32. 32.Find the value of x² + 2xy + y² when x = 9 and y = 4.
  33. 33.Use a² − b² = (a + b)(a − b) to find 92² − 25².
  34. 34.If a + b = 7 and ab = 10, what is a² + b²?
  35. 35.Use (a + b)² = a² + 2ab + b² to find 93².
  36. 36.Use (a − b)² = a² − 2ab + b² to find 46².
  37. 37.Use (a + b)(a − b) = a² − b² to find 85 × 75.
  38. 38.Use a² − b² = (a + b)(a − b) to find 22² − 13².
  39. 39.Find the value of x² − y² when x = 15 and y = 14.
  40. 40.Use a² − b² = (a + b)(a − b) to find 80² − 65².

Answer key

  1. 121
  2. 4356
  3. 144
  4. 10
  5. 729
  6. 10
  7. 5
  8. 147
  9. 165
  10. 1785
  11. 4899
  12. 3721
  13. 1024
  14. 3249
  15. 8836
  16. 1599
  17. 1089
  18. 5041
  19. 4761
  20. 9216
  21. 81
  22. 256
  23. 5929
  24. 265
  25. 6561
  26. 6240
  27. 875
  28. 484
  29. 324
  30. 3481
  31. 58
  32. 169
  33. 7839
  34. 29
  35. 8649
  36. 2116
  37. 6375
  38. 315
  39. 29
  40. 2175

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