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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 139 · 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)² = a² − 2ab + b² to find 28².
  2. 2.Use a² − b² = (a + b)(a − b) to find 54² − 42².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 59².
  4. 4.Use (a − b)² = a² − 2ab + b² to find 63².
  5. 5.If a − b = 2 and ab = 3, what is a² + b²?
  6. 6.Use (a + b)² = a² + 2ab + b² to find 82².
  7. 7.Find the value of x² − 2xy + y² when x = 7 and y = 3.
  8. 8.Use (a − b)² = a² − 2ab + b² to find 56².
  9. 9.Find the value of x² − y² when x = 9 and y = 3.
  10. 10.Use (a − b)² = a² − 2ab + b² to find 58².
  11. 11.Use (a + b)² = a² + 2ab + b² to find 14².
  12. 12.Find the value of x² − 2xy + y² when x = 4 and y = 1.
  13. 13.Use a² − b² = (a + b)(a − b) to find 41² − 33².
  14. 14.Use a² − b² = (a + b)(a − b) to find 37² − 12².
  15. 15.Use a² − b² = (a + b)(a − b) to find 31² − 25².
  16. 16.Find the value of x² − 2xy + y² when x = 11 and y = 6.
  17. 17.Use (a + b)(a − b) = a² − b² to find 103 × 97.
  18. 18.Use (a + b)(a − b) = a² − b² to find 95 × 85.
  19. 19.Use (a − b)² = a² − 2ab + b² to find 37².
  20. 20.Use (a + b)(a − b) = a² − b² to find 23 × 17.
  21. 21.If a − b = 5 and ab = 24, what is a² + b²?
  22. 22.Use (a + b)² = a² + 2ab + b² to find 69².
  23. 23.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  24. 24.Use (a + b)² = a² + 2ab + b² to find 52².
  25. 25.Use (a + b)² = a² + 2ab + b² to find 58².
  26. 26.Use (a − b)² = a² − 2ab + b² to find 67².
  27. 27.Find the value of x² − 2xy + y² when x = 4 and y = 2.
  28. 28.If a + b = 5 and ab = 6, what is a² + b²?
  29. 29.If a + b = 14 and ab = 45, what is a² + b²?
  30. 30.Use (a − b)² = a² − 2ab + b² to find 98².
  31. 31.Use (a + b)(a − b) = a² − b² to find 36 × 24.
  32. 32.Use (a − b)² = a² − 2ab + b² to find 43².
  33. 33.If a + b = 3 and ab = 2, what is a² + b²?
  34. 34.Use (a + b)(a − b) = a² − b² to find 107 × 93.
  35. 35.Use (a + b)(a − b) = a² − b² to find 52 × 48.
  36. 36.Use (a − b)² = a² − 2ab + b² to find 93².
  37. 37.Find the value of x² + 2xy + y² when x = 9 and y = 6.
  38. 38.Find the value of x² − 2xy + y² when x = 14 and y = 13.
  39. 39.Use (a − b)² = a² − 2ab + b² to find 94².
  40. 40.If a − b = 3 and ab = 4, what is a² + b²?

Answer key

  1. 784
  2. 1152
  3. 3481
  4. 3969
  5. 10
  6. 6724
  7. 16
  8. 3136
  9. 72
  10. 3364
  11. 196
  12. 9
  13. 592
  14. 1225
  15. 336
  16. 25
  17. 9991
  18. 8075
  19. 1369
  20. 391
  21. 73
  22. 4761
  23. 899
  24. 2704
  25. 3364
  26. 4489
  27. 4
  28. 13
  29. 106
  30. 9604
  31. 864
  32. 1849
  33. 5
  34. 9951
  35. 2496
  36. 8649
  37. 225
  38. 1
  39. 8836
  40. 17

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