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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 397 · 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 31².
  2. 2.Use (a + b)(a − b) = a² − b² to find 87 × 73.
  3. 3.Find the value of x² − y² when x = 14 and y = 11.
  4. 4.Use (a + b)(a − b) = a² − b² to find 83 × 77.
  5. 5.Use (a + b)(a − b) = a² − b² to find 106 × 94.
  6. 6.Use a² − b² = (a + b)(a − b) to find 89² − 6².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 96².
  8. 8.Use a² − b² = (a + b)(a − b) to find 24² − 15².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 64².
  10. 10.Use (a + b)(a − b) = a² − b² to find 22 × 18.
  11. 11.If a + b = 14 and ab = 33, what is a² + b²?
  12. 12.If a + b = 13 and ab = 42, what is a² + b²?
  13. 13.If a − b = 2 and ab = 15, what is a² + b²?
  14. 14.Use (a + b)(a − b) = a² − b² to find 102 × 98.
  15. 15.Use a² − b² = (a + b)(a − b) to find 60² − 28².
  16. 16.Use (a − b)² = a² − 2ab + b² to find 11².
  17. 17.Find the value of x² − 2xy + y² when x = 12 and y = 11.
  18. 18.Use (a − b)² = a² − 2ab + b² to find 36².
  19. 19.Use (a + b)(a − b) = a² − b² to find 56 × 44.
  20. 20.Find the value of x² − 2xy + y² when x = 4 and y = 1.
  21. 21.Use (a + b)(a − b) = a² − b² to find 73 × 67.
  22. 22.Use a² − b² = (a + b)(a − b) to find 20² − 18².
  23. 23.If a − b = 1 and ab = 20, what is a² + b²?
  24. 24.If a − b = 2 and ab = 35, what is a² + b²?
  25. 25.If a + b = 10 and ab = 9, what is a² + b²?
  26. 26.Use (a + b)² = a² + 2ab + b² to find 35².
  27. 27.Find the value of x² + 2xy + y² when x = 9 and y = 8.
  28. 28.Use a² − b² = (a + b)(a − b) to find 65² − 7².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 92².
  30. 30.Find the value of x² − 2xy + y² when x = 14 and y = 3.
  31. 31.Use (a + b)(a − b) = a² − b² to find 99 × 81.
  32. 32.Find the value of x² + 2xy + y² when x = 12 and y = 7.
  33. 33.Use (a + b)² = a² + 2ab + b² to find 85².
  34. 34.Use a² − b² = (a + b)(a − b) to find 43² − 38².
  35. 35.Use (a − b)² = a² − 2ab + b² to find 76².
  36. 36.Use a² − b² = (a + b)(a − b) to find 48² − 46².
  37. 37.If a + b = 5 and ab = 6, what is a² + b²?
  38. 38.Use (a − b)² = a² − 2ab + b² to find 99².
  39. 39.Use (a − b)² = a² − 2ab + b² to find 43².
  40. 40.Find the value of x² + 2xy + y² when x = 15 and y = 13.

Answer key

  1. 961
  2. 6351
  3. 75
  4. 6391
  5. 9964
  6. 7885
  7. 9216
  8. 351
  9. 4096
  10. 396
  11. 130
  12. 85
  13. 34
  14. 9996
  15. 2816
  16. 121
  17. 1
  18. 1296
  19. 2464
  20. 9
  21. 4891
  22. 76
  23. 41
  24. 74
  25. 82
  26. 1225
  27. 289
  28. 4176
  29. 8464
  30. 121
  31. 8019
  32. 361
  33. 7225
  34. 405
  35. 5776
  36. 188
  37. 13
  38. 9801
  39. 1849
  40. 784

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