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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 361 · 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 106 × 94.
  2. 2.If a + b = 6 and ab = 8, what is a² + b²?
  3. 3.If a − b = 2 and ab = 24, what is a² + b²?
  4. 4.If a − b = 1 and ab = 2, what is a² + b²?
  5. 5.Use a² − b² = (a + b)(a − b) to find 94² − 14².
  6. 6.Use (a + b)² = a² + 2ab + b² to find 15².
  7. 7.Use a² − b² = (a + b)(a − b) to find 39² − 23².
  8. 8.Find the value of x² − y² when x = 7 and y = 6.
  9. 9.Find the value of x² + 2xy + y² when x = 6 and y = 3.
  10. 10.Use a² − b² = (a + b)(a − b) to find 90² − 5².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 76².
  12. 12.Use a² − b² = (a + b)(a − b) to find 82² − 10².
  13. 13.If a − b = 2 and ab = 8, what is a² + b²?
  14. 14.Use a² − b² = (a + b)(a − b) to find 28² − 11².
  15. 15.Find the value of x² − 2xy + y² when x = 15 and y = 12.
  16. 16.Use (a + b)² = a² + 2ab + b² to find 39².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 57².
  18. 18.Use (a + b)(a − b) = a² − b² to find 63 × 57.
  19. 19.Use (a − b)² = a² − 2ab + b² to find 36².
  20. 20.Use (a + b)(a − b) = a² − b² to find 46 × 34.
  21. 21.Use (a + b)² = a² + 2ab + b² to find 91².
  22. 22.Use (a − b)² = a² − 2ab + b² to find 66².
  23. 23.Use (a − b)² = a² − 2ab + b² to find 69².
  24. 24.Use (a − b)² = a² − 2ab + b² to find 68².
  25. 25.Use a² − b² = (a + b)(a − b) to find 38² − 15².
  26. 26.Use a² − b² = (a + b)(a − b) to find 92² − 36².
  27. 27.Find the value of x² + 2xy + y² when x = 14 and y = 4.
  28. 28.Use (a − b)² = a² − 2ab + b² to find 47².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 84².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 43².
  31. 31.Use (a + b)² = a² + 2ab + b² to find 92².
  32. 32.If a − b = 2 and ab = 3, what is a² + b²?
  33. 33.Find the value of x² − y² when x = 12 and y = 2.
  34. 34.Use a² − b² = (a + b)(a − b) to find 63² − 33².
  35. 35.Find the value of x² − 2xy + y² when x = 7 and y = 1.
  36. 36.Use (a − b)² = a² − 2ab + b² to find 32².
  37. 37.Find the value of x² + 2xy + y² when x = 8 and y = 3.
  38. 38.Use a² − b² = (a + b)(a − b) to find 24² − 18².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 36².
  40. 40.Use (a + b)(a − b) = a² − b² to find 21 × 19.

Answer key

  1. 9964
  2. 20
  3. 52
  4. 5
  5. 8640
  6. 225
  7. 992
  8. 13
  9. 81
  10. 8075
  11. 5776
  12. 6624
  13. 20
  14. 663
  15. 9
  16. 1521
  17. 3249
  18. 3591
  19. 1296
  20. 1564
  21. 8281
  22. 4356
  23. 4761
  24. 4624
  25. 1219
  26. 7168
  27. 324
  28. 2209
  29. 7056
  30. 1849
  31. 8464
  32. 10
  33. 140
  34. 2880
  35. 36
  36. 1024
  37. 121
  38. 252
  39. 1296
  40. 399

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