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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 969 · 40 sums
TalentJR

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 86 × 74.
  2. 2.If a + b = 9 and ab = 20, what is a² + b²?
  3. 3.Use a² − b² = (a + b)(a − b) to find 92² − 14².
  4. 4.Use (a + b)² = a² + 2ab + b² to find 22².
  5. 5.Use a² − b² = (a + b)(a − b) to find 52² − 12².
  6. 6.Use (a + b)(a − b) = a² − b² to find 57 × 43.
  7. 7.Use (a − b)² = a² − 2ab + b² to find 75².
  8. 8.Use a² − b² = (a + b)(a − b) to find 56² − 44².
  9. 9.Find the value of x² − 2xy + y² when x = 12 and y = 3.
  10. 10.Use (a + b)² = a² + 2ab + b² to find 44².
  11. 11.Use (a + b)(a − b) = a² − b² to find 27 × 13.
  12. 12.If a − b = 7 and ab = 44, what is a² + b²?
  13. 13.Find the value of x² − y² when x = 12 and y = 4.
  14. 14.Use (a + b)² = a² + 2ab + b² to find 38².
  15. 15.Use (a + b)(a − b) = a² − b² to find 23 × 17.
  16. 16.If a − b = 1 and ab = 2, what is a² + b²?
  17. 17.Use a² − b² = (a + b)(a − b) to find 40² − 19².
  18. 18.If a + b = 7 and ab = 10, what is a² + b²?
  19. 19.Use a² − b² = (a + b)(a − b) to find 22² − 1².
  20. 20.Use a² − b² = (a + b)(a − b) to find 59² − 53².
  21. 21.Use (a + b)² = a² + 2ab + b² to find 63².
  22. 22.If a + b = 3 and ab = 2, what is a² + b²?
  23. 23.Use (a + b)(a − b) = a² − b² to find 71 × 69.
  24. 24.Use (a + b)² = a² + 2ab + b² to find 85².
  25. 25.Use (a + b)² = a² + 2ab + b² to find 16².
  26. 26.Find the value of x² + 2xy + y² when x = 11 and y = 1.
  27. 27.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  28. 28.Use (a − b)² = a² − 2ab + b² to find 35².
  29. 29.Use (a − b)² = a² − 2ab + b² to find 31².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 109².
  31. 31.Use (a + b)² = a² + 2ab + b² to find 101².
  32. 32.If a − b = 3 and ab = 54, what is a² + b²?
  33. 33.Use a² − b² = (a + b)(a − b) to find 97² − 68².
  34. 34.If a + b = 15 and ab = 50, what is a² + b²?
  35. 35.Use (a + b)² = a² + 2ab + b² to find 99².
  36. 36.Use (a − b)² = a² − 2ab + b² to find 94².
  37. 37.Use (a + b)² = a² + 2ab + b² to find 23².
  38. 38.Find the value of x² + 2xy + y² when x = 13 and y = 12.
  39. 39.Use (a + b)² = a² + 2ab + b² to find 12².
  40. 40.If a − b = 4 and ab = 5, what is a² + b²?

Answer key

  1. 6364
  2. 41
  3. 8268
  4. 484
  5. 2560
  6. 2451
  7. 5625
  8. 1200
  9. 81
  10. 1936
  11. 351
  12. 137
  13. 128
  14. 1444
  15. 391
  16. 5
  17. 1239
  18. 29
  19. 483
  20. 672
  21. 3969
  22. 5
  23. 4899
  24. 7225
  25. 256
  26. 144
  27. 899
  28. 1225
  29. 961
  30. 11881
  31. 10201
  32. 117
  33. 4785
  34. 125
  35. 9801
  36. 8836
  37. 529
  38. 625
  39. 144
  40. 26

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