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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 95 · 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 a² − b² = (a + b)(a − b) to find 60² − 11².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 73².
  3. 3.Use (a + b)² = a² + 2ab + b² to find 76².
  4. 4.Use (a + b)(a − b) = a² − b² to find 66 × 54.
  5. 5.Use (a + b)² = a² + 2ab + b² to find 62².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 38².
  7. 7.Use (a − b)² = a² − 2ab + b² to find 28².
  8. 8.If a + b = 11 and ab = 24, what is a² + b²?
  9. 9.Use (a − b)² = a² − 2ab + b² to find 43².
  10. 10.Use (a + b)(a − b) = a² − b² to find 36 × 24.
  11. 11.Use (a + b)(a − b) = a² − b² to find 89 × 71.
  12. 12.Use (a − b)² = a² − 2ab + b² to find 44².
  13. 13.If a + b = 14 and ab = 48, what is a² + b²?
  14. 14.Use (a + b)(a − b) = a² − b² to find 105 × 95.
  15. 15.Use (a + b)(a − b) = a² − b² to find 22 × 18.
  16. 16.Use (a + b)² = a² + 2ab + b² to find 105².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 88².
  18. 18.If a + b = 10 and ab = 21, what is a² + b²?
  19. 19.Use (a − b)² = a² − 2ab + b² to find 17².
  20. 20.Find the value of x² − 2xy + y² when x = 6 and y = 1.
  21. 21.Use (a + b)² = a² + 2ab + b² to find 106².
  22. 22.Find the value of x² − 2xy + y² when x = 9 and y = 3.
  23. 23.Use (a + b)(a − b) = a² − b² to find 52 × 48.
  24. 24.If a + b = 5 and ab = 4, what is a² + b²?
  25. 25.Use (a + b)² = a² + 2ab + b² to find 77².
  26. 26.Use (a + b)(a − b) = a² − b² to find 44 × 36.
  27. 27.Use (a − b)² = a² − 2ab + b² to find 48².
  28. 28.If a − b = 2 and ab = 24, what is a² + b²?
  29. 29.Use a² − b² = (a + b)(a − b) to find 93² − 70².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 99².
  31. 31.Use (a − b)² = a² − 2ab + b² to find 72².
  32. 32.Use a² − b² = (a + b)(a − b) to find 58² − 12².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 12².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 36².
  35. 35.Use (a + b)(a − b) = a² − b² to find 83 × 77.
  36. 36.Find the value of x² − y² when x = 3 and y = 1.
  37. 37.Find the value of x² − 2xy + y² when x = 11 and y = 1.
  38. 38.Use a² − b² = (a + b)(a − b) to find 98² − 34².
  39. 39.Use (a + b)(a − b) = a² − b² to find 64 × 56.
  40. 40.Find the value of x² − y² when x = 14 and y = 6.

Answer key

  1. 3479
  2. 5329
  3. 5776
  4. 3564
  5. 3844
  6. 1444
  7. 784
  8. 73
  9. 1849
  10. 864
  11. 6319
  12. 1936
  13. 100
  14. 9975
  15. 396
  16. 11025
  17. 7744
  18. 58
  19. 289
  20. 25
  21. 11236
  22. 36
  23. 2496
  24. 17
  25. 5929
  26. 1584
  27. 2304
  28. 52
  29. 3749
  30. 9801
  31. 5184
  32. 3220
  33. 144
  34. 1296
  35. 6391
  36. 8
  37. 100
  38. 8448
  39. 3584
  40. 160

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