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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 223 · 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 = 8 and y = 3.
  2. 2.Use a² − b² = (a + b)(a − b) to find 52² − 10².
  3. 3.Use a² − b² = (a + b)(a − b) to find 65² − 23².
  4. 4.Use (a + b)² = a² + 2ab + b² to find 41².
  5. 5.Use (a + b)(a − b) = a² − b² to find 23 × 17.
  6. 6.Use (a − b)² = a² − 2ab + b² to find 18².
  7. 7.If a + b = 11 and ab = 28, what is a² + b²?
  8. 8.Use (a + b)(a − b) = a² − b² to find 59 × 41.
  9. 9.Use a² − b² = (a + b)(a − b) to find 30² − 21².
  10. 10.Use a² − b² = (a + b)(a − b) to find 42² − 17².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 81².
  12. 12.Use a² − b² = (a + b)(a − b) to find 36² − 30².
  13. 13.Use (a − b)² = a² − 2ab + b² to find 94².
  14. 14.Use a² − b² = (a + b)(a − b) to find 35² − 15².
  15. 15.Use (a + b)(a − b) = a² − b² to find 83 × 77.
  16. 16.Use (a − b)² = a² − 2ab + b² to find 68².
  17. 17.Use (a + b)(a − b) = a² − b² to find 101 × 99.
  18. 18.Find the value of x² + 2xy + y² when x = 10 and y = 1.
  19. 19.Find the value of x² − 2xy + y² when x = 9 and y = 3.
  20. 20.If a + b = 18 and ab = 72, what is a² + b²?
  21. 21.Use (a − b)² = a² − 2ab + b² to find 35².
  22. 22.If a − b = 5 and ab = 50, what is a² + b²?
  23. 23.Use (a + b)(a − b) = a² − b² to find 99 × 81.
  24. 24.Use (a − b)² = a² − 2ab + b² to find 62².
  25. 25.Use (a + b)(a − b) = a² − b² to find 64 × 56.
  26. 26.Use (a + b)² = a² + 2ab + b² to find 18².
  27. 27.If a + b = 12 and ab = 27, what is a² + b²?
  28. 28.Find the value of x² − y² when x = 7 and y = 1.
  29. 29.Use (a − b)² = a² − 2ab + b² to find 73².
  30. 30.Use a² − b² = (a + b)(a − b) to find 38² − 14².
  31. 31.Find the value of x² − y² when x = 7 and y = 6.
  32. 32.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  33. 33.Use a² − b² = (a + b)(a − b) to find 48² − 30².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 11².
  35. 35.Find the value of x² + 2xy + y² when x = 9 and y = 8.
  36. 36.Find the value of x² − y² when x = 11 and y = 1.
  37. 37.Use (a + b)² = a² + 2ab + b² to find 43².
  38. 38.Use (a + b)² = a² + 2ab + b² to find 31².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 34².
  40. 40.Use (a + b)² = a² + 2ab + b² to find 38².

Answer key

  1. 121
  2. 2604
  3. 3696
  4. 1681
  5. 391
  6. 324
  7. 65
  8. 2419
  9. 459
  10. 1475
  11. 6561
  12. 396
  13. 8836
  14. 1000
  15. 6391
  16. 4624
  17. 9999
  18. 121
  19. 36
  20. 180
  21. 1225
  22. 125
  23. 8019
  24. 3844
  25. 3584
  26. 324
  27. 90
  28. 48
  29. 5329
  30. 1248
  31. 13
  32. 25
  33. 1404
  34. 121
  35. 289
  36. 120
  37. 1849
  38. 961
  39. 1156
  40. 1444

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