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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 118 · 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 55 × 45.
  2. 2.Find the value of x² − y² when x = 13 and y = 10.
  3. 3.Find the value of x² + 2xy + y² when x = 5 and y = 1.
  4. 4.Use a² − b² = (a + b)(a − b) to find 83² − 5².
  5. 5.Find the value of x² − y² when x = 11 and y = 8.
  6. 6.Use (a + b)² = a² + 2ab + b² to find 32².
  7. 7.Use (a − b)² = a² − 2ab + b² to find 91².
  8. 8.Use (a − b)² = a² − 2ab + b² to find 38².
  9. 9.Use a² − b² = (a + b)(a − b) to find 83² − 64².
  10. 10.Use a² − b² = (a + b)(a − b) to find 58² − 13².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 86².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 93².
  13. 13.If a − b = 9 and ab = 10, what is a² + b²?
  14. 14.Find the value of x² − 2xy + y² when x = 6 and y = 2.
  15. 15.Use a² − b² = (a + b)(a − b) to find 26² − 10².
  16. 16.Use a² − b² = (a + b)(a − b) to find 31² − 20².
  17. 17.Use a² − b² = (a + b)(a − b) to find 99² − 36².
  18. 18.Find the value of x² + 2xy + y² when x = 12 and y = 10.
  19. 19.Use (a − b)² = a² − 2ab + b² to find 73².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 18².
  21. 21.Use (a + b)² = a² + 2ab + b² to find 91².
  22. 22.Find the value of x² + 2xy + y² when x = 4 and y = 3.
  23. 23.Use (a + b)² = a² + 2ab + b² to find 84².
  24. 24.Use a² − b² = (a + b)(a − b) to find 95² − 34².
  25. 25.Use (a + b)² = a² + 2ab + b² to find 99².
  26. 26.If a + b = 7 and ab = 6, what is a² + b²?
  27. 27.Use (a + b)² = a² + 2ab + b² to find 98².
  28. 28.If a + b = 23 and ab = 132, what is a² + b²?
  29. 29.Use (a + b)(a − b) = a² − b² to find 84 × 76.
  30. 30.Use (a + b)² = a² + 2ab + b² to find 14².
  31. 31.Use (a + b)(a − b) = a² − b² to find 88 × 72.
  32. 32.Use (a − b)² = a² − 2ab + b² to find 43².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 85².
  34. 34.Find the value of x² − 2xy + y² when x = 5 and y = 3.
  35. 35.Use (a + b)² = a² + 2ab + b² to find 54².
  36. 36.Use a² − b² = (a + b)(a − b) to find 84² − 25².
  37. 37.Use (a + b)(a − b) = a² − b² to find 47 × 33.
  38. 38.Use a² − b² = (a + b)(a − b) to find 32² − 13².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 67².
  40. 40.Find the value of x² − 2xy + y² when x = 4 and y = 1.

Answer key

  1. 2475
  2. 69
  3. 36
  4. 6864
  5. 57
  6. 1024
  7. 8281
  8. 1444
  9. 2793
  10. 3195
  11. 7396
  12. 8649
  13. 101
  14. 16
  15. 576
  16. 561
  17. 8505
  18. 484
  19. 5329
  20. 324
  21. 8281
  22. 49
  23. 7056
  24. 7869
  25. 9801
  26. 37
  27. 9604
  28. 265
  29. 6384
  30. 196
  31. 6336
  32. 1849
  33. 7225
  34. 4
  35. 2916
  36. 6431
  37. 1551
  38. 855
  39. 4489
  40. 9

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