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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 700 · 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 71².
  2. 2.Use (a − b)² = a² − 2ab + b² to find 94².
  3. 3.Use a² − b² = (a + b)(a − b) to find 89² − 19².
  4. 4.Find the value of x² + 2xy + y² when x = 8 and y = 1.
  5. 5.Use (a + b)(a − b) = a² − b² to find 42 × 38.
  6. 6.Use (a + b)² = a² + 2ab + b² to find 35².
  7. 7.If a + b = 20 and ab = 99, what is a² + b²?
  8. 8.Use a² − b² = (a + b)(a − b) to find 84² − 3².
  9. 9.Find the value of x² − y² when x = 7 and y = 4.
  10. 10.Use (a − b)² = a² − 2ab + b² to find 32².
  11. 11.If a − b = 3 and ab = 88, what is a² + b²?
  12. 12.If a + b = 11 and ab = 18, what is a² + b²?
  13. 13.Use (a + b)² = a² + 2ab + b² to find 39².
  14. 14.Use (a + b)² = a² + 2ab + b² to find 81².
  15. 15.Use (a + b)² = a² + 2ab + b² to find 41².
  16. 16.Find the value of x² − y² when x = 12 and y = 1.
  17. 17.If a + b = 3 and ab = 2, what is a² + b²?
  18. 18.Use (a + b)(a − b) = a² − b² to find 76 × 64.
  19. 19.If a − b = 3 and ab = 28, what is a² + b²?
  20. 20.Use (a + b)² = a² + 2ab + b² to find 63².
  21. 21.Use (a − b)² = a² − 2ab + b² to find 47².
  22. 22.If a − b = 8 and ab = 33, what is a² + b²?
  23. 23.Use (a + b)(a − b) = a² − b² to find 66 × 54.
  24. 24.Use a² − b² = (a + b)(a − b) to find 25² − 18².
  25. 25.Use a² − b² = (a + b)(a − b) to find 38² − 5².
  26. 26.Use (a − b)² = a² − 2ab + b² to find 92².
  27. 27.Use a² − b² = (a + b)(a − b) to find 96² − 57².
  28. 28.Use (a − b)² = a² − 2ab + b² to find 95².
  29. 29.If a − b = 2 and ab = 8, what is a² + b²?
  30. 30.Use (a − b)² = a² − 2ab + b² to find 44².
  31. 31.Use (a + b)(a − b) = a² − b² to find 98 × 82.
  32. 32.Use a² − b² = (a + b)(a − b) to find 83² − 17².
  33. 33.Find the value of x² − y² when x = 9 and y = 2.
  34. 34.If a − b = 3 and ab = 18, what is a² + b²?
  35. 35.If a + b = 6 and ab = 5, what is a² + b²?
  36. 36.Use (a + b)² = a² + 2ab + b² to find 95².
  37. 37.Use (a + b)(a − b) = a² − b² to find 52 × 48.
  38. 38.Use a² − b² = (a + b)(a − b) to find 23² − 10².
  39. 39.Find the value of x² − y² when x = 3 and y = 2.
  40. 40.Find the value of x² + 2xy + y² when x = 11 and y = 6.

Answer key

  1. 5041
  2. 8836
  3. 7560
  4. 81
  5. 1596
  6. 1225
  7. 202
  8. 7047
  9. 33
  10. 1024
  11. 185
  12. 85
  13. 1521
  14. 6561
  15. 1681
  16. 143
  17. 5
  18. 4864
  19. 65
  20. 3969
  21. 2209
  22. 130
  23. 3564
  24. 301
  25. 1419
  26. 8464
  27. 5967
  28. 9025
  29. 20
  30. 1936
  31. 8036
  32. 6600
  33. 77
  34. 45
  35. 26
  36. 9025
  37. 2496
  38. 429
  39. 5
  40. 289

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