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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 309 · 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 = 2.
  2. 2.Use (a − b)² = a² − 2ab + b² to find 77².
  3. 3.Use (a + b)² = a² + 2ab + b² to find 18².
  4. 4.Use a² − b² = (a + b)(a − b) to find 99² − 1².
  5. 5.Use (a + b)(a − b) = a² − b² to find 51 × 49.
  6. 6.Use (a + b)(a − b) = a² − b² to find 87 × 73.
  7. 7.Use (a − b)² = a² − 2ab + b² to find 37².
  8. 8.Use (a − b)² = a² − 2ab + b² to find 39².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 24².
  10. 10.If a + b = 3 and ab = 2, what is a² + b²?
  11. 11.If a + b = 5 and ab = 4, what is a² + b²?
  12. 12.Use (a + b)² = a² + 2ab + b² to find 17².
  13. 13.Use a² − b² = (a + b)(a − b) to find 42² − 20².
  14. 14.Find the value of x² − y² when x = 5 and y = 2.
  15. 15.Use (a + b)(a − b) = a² − b² to find 65 × 55.
  16. 16.Use (a + b)² = a² + 2ab + b² to find 72².
  17. 17.Use a² − b² = (a + b)(a − b) to find 42² − 12².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 54².
  19. 19.Find the value of x² + 2xy + y² when x = 13 and y = 7.
  20. 20.Find the value of x² − 2xy + y² when x = 15 and y = 7.
  21. 21.Use (a − b)² = a² − 2ab + b² to find 88².
  22. 22.Use a² − b² = (a + b)(a − b) to find 43² − 31².
  23. 23.Use (a + b)² = a² + 2ab + b² to find 26².
  24. 24.Use a² − b² = (a + b)(a − b) to find 29² − 16².
  25. 25.Use (a − b)² = a² − 2ab + b² to find 31².
  26. 26.Use (a + b)² = a² + 2ab + b² to find 105².
  27. 27.Use (a + b)² = a² + 2ab + b² to find 48².
  28. 28.Use (a − b)² = a² − 2ab + b² to find 55².
  29. 29.If a + b = 5 and ab = 6, what is a² + b²?
  30. 30.Use a² − b² = (a + b)(a − b) to find 62² − 51².
  31. 31.Use (a + b)² = a² + 2ab + b² to find 11².
  32. 32.If a + b = 9 and ab = 14, what is a² + b²?
  33. 33.Use (a − b)² = a² − 2ab + b² to find 69².
  34. 34.Use (a − b)² = a² − 2ab + b² to find 19².
  35. 35.Use (a − b)² = a² − 2ab + b² to find 35².
  36. 36.Find the value of x² − 2xy + y² when x = 15 and y = 12.
  37. 37.Use (a − b)² = a² − 2ab + b² to find 84².
  38. 38.Use (a + b)(a − b) = a² − b² to find 59 × 41.
  39. 39.Use (a + b)² = a² + 2ab + b² to find 69².
  40. 40.Use (a − b)² = a² − 2ab + b² to find 46².

Answer key

  1. 16
  2. 5929
  3. 324
  4. 9800
  5. 2499
  6. 6351
  7. 1369
  8. 1521
  9. 576
  10. 5
  11. 17
  12. 289
  13. 1364
  14. 21
  15. 3575
  16. 5184
  17. 1620
  18. 2916
  19. 400
  20. 64
  21. 7744
  22. 888
  23. 676
  24. 585
  25. 961
  26. 11025
  27. 2304
  28. 3025
  29. 13
  30. 1243
  31. 121
  32. 53
  33. 4761
  34. 361
  35. 1225
  36. 9
  37. 7056
  38. 2419
  39. 4761
  40. 2116

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