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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 111 · 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 73².
  2. 2.Use (a − b)² = a² − 2ab + b² to find 26².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 36².
  4. 4.Use a² − b² = (a + b)(a − b) to find 63² − 14².
  5. 5.Use (a + b)² = a² + 2ab + b² to find 64².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 58².
  7. 7.If a − b = 8 and ab = 20, what is a² + b²?
  8. 8.Use (a + b)² = a² + 2ab + b² to find 58².
  9. 9.If a + b = 16 and ab = 60, what is a² + b²?
  10. 10.Find the value of x² − y² when x = 5 and y = 1.
  11. 11.Use (a + b)² = a² + 2ab + b² to find 72².
  12. 12.If a − b = 8 and ab = 48, what is a² + b²?
  13. 13.Use (a − b)² = a² − 2ab + b² to find 59².
  14. 14.Use (a + b)² = a² + 2ab + b² to find 56².
  15. 15.Use (a + b)² = a² + 2ab + b² to find 43².
  16. 16.If a − b = 7 and ab = 44, what is a² + b²?
  17. 17.If a − b = 1 and ab = 6, what is a² + b²?
  18. 18.Find the value of x² − y² when x = 6 and y = 1.
  19. 19.If a + b = 14 and ab = 48, what is a² + b²?
  20. 20.Find the value of x² − 2xy + y² when x = 4 and y = 1.
  21. 21.If a − b = 1 and ab = 42, what is a² + b²?
  22. 22.Use (a + b)² = a² + 2ab + b² to find 33².
  23. 23.Use (a − b)² = a² − 2ab + b² to find 39².
  24. 24.Find the value of x² − y² when x = 8 and y = 6.
  25. 25.Use a² − b² = (a + b)(a − b) to find 90² − 73².
  26. 26.Use (a + b)² = a² + 2ab + b² to find 15².
  27. 27.If a + b = 14 and ab = 45, what is a² + b²?
  28. 28.Use (a + b)(a − b) = a² − b² to find 46 × 34.
  29. 29.Use (a + b)² = a² + 2ab + b² to find 55².
  30. 30.If a − b = 2 and ab = 63, what is a² + b²?
  31. 31.Use (a + b)(a − b) = a² − b² to find 75 × 65.
  32. 32.Use (a − b)² = a² − 2ab + b² to find 28².
  33. 33.Use a² − b² = (a + b)(a − b) to find 36² − 10².
  34. 34.Use a² − b² = (a + b)(a − b) to find 35² − 7².
  35. 35.Use (a − b)² = a² − 2ab + b² to find 94².
  36. 36.Use (a − b)² = a² − 2ab + b² to find 16².
  37. 37.Use (a + b)(a − b) = a² − b² to find 69 × 51.
  38. 38.Use (a − b)² = a² − 2ab + b² to find 93².
  39. 39.If a − b = 2 and ab = 3, what is a² + b²?
  40. 40.Find the value of x² + 2xy + y² when x = 14 and y = 7.

Answer key

  1. 5329
  2. 676
  3. 1296
  4. 3773
  5. 4096
  6. 3364
  7. 104
  8. 3364
  9. 136
  10. 24
  11. 5184
  12. 160
  13. 3481
  14. 3136
  15. 1849
  16. 137
  17. 13
  18. 35
  19. 100
  20. 9
  21. 85
  22. 1089
  23. 1521
  24. 28
  25. 2771
  26. 225
  27. 106
  28. 1564
  29. 3025
  30. 130
  31. 4875
  32. 784
  33. 1196
  34. 1176
  35. 8836
  36. 256
  37. 3519
  38. 8649
  39. 10
  40. 441

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