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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 36 · 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 104 × 96.
  2. 2.Use (a + b)(a − b) = a² − b² to find 79 × 61.
  3. 3.Use (a + b)(a − b) = a² − b² to find 27 × 13.
  4. 4.Use (a + b)² = a² + 2ab + b² to find 26².
  5. 5.Use a² − b² = (a + b)(a − b) to find 85² − 25².
  6. 6.Use a² − b² = (a + b)(a − b) to find 61² − 11².
  7. 7.If a + b = 7 and ab = 12, what is a² + b²?
  8. 8.Use (a − b)² = a² − 2ab + b² to find 28².
  9. 9.If a + b = 15 and ab = 56, what is a² + b²?
  10. 10.If a − b = 2 and ab = 24, what is a² + b²?
  11. 11.Use (a − b)² = a² − 2ab + b² to find 59².
  12. 12.Use (a + b)² = a² + 2ab + b² to find 13².
  13. 13.Use a² − b² = (a + b)(a − b) to find 49² − 32².
  14. 14.Find the value of x² − 2xy + y² when x = 13 and y = 12.
  15. 15.If a + b = 13 and ab = 36, what is a² + b²?
  16. 16.Use (a − b)² = a² − 2ab + b² to find 32².
  17. 17.Use a² − b² = (a + b)(a − b) to find 73² − 44².
  18. 18.Find the value of x² − y² when x = 12 and y = 11.
  19. 19.Use (a − b)² = a² − 2ab + b² to find 75².
  20. 20.Use (a + b)(a − b) = a² − b² to find 21 × 19.
  21. 21.Use (a + b)² = a² + 2ab + b² to find 67².
  22. 22.Find the value of x² − 2xy + y² when x = 12 and y = 4.
  23. 23.Find the value of x² − 2xy + y² when x = 4 and y = 1.
  24. 24.Find the value of x² − 2xy + y² when x = 5 and y = 3.
  25. 25.Use (a + b)(a − b) = a² − b² to find 38 × 22.
  26. 26.If a + b = 11 and ab = 28, what is a² + b²?
  27. 27.Find the value of x² + 2xy + y² when x = 11 and y = 1.
  28. 28.Use (a − b)² = a² − 2ab + b² to find 85².
  29. 29.If a + b = 6 and ab = 8, what is a² + b²?
  30. 30.If a − b = 7 and ab = 30, what is a² + b²?
  31. 31.Use (a + b)² = a² + 2ab + b² to find 92².
  32. 32.Use (a + b)(a − b) = a² − b² to find 83 × 77.
  33. 33.Use (a + b)(a − b) = a² − b² to find 48 × 32.
  34. 34.Find the value of x² − y² when x = 4 and y = 2.
  35. 35.Use a² − b² = (a + b)(a − b) to find 99² − 55².
  36. 36.Use (a − b)² = a² − 2ab + b² to find 63².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 48².
  38. 38.Find the value of x² + 2xy + y² when x = 14 and y = 6.
  39. 39.If a − b = 1 and ab = 6, what is a² + b²?
  40. 40.Find the value of x² − 2xy + y² when x = 12 and y = 11.

Answer key

  1. 9984
  2. 4819
  3. 351
  4. 676
  5. 6600
  6. 3600
  7. 25
  8. 784
  9. 113
  10. 52
  11. 3481
  12. 169
  13. 1377
  14. 1
  15. 97
  16. 1024
  17. 3393
  18. 23
  19. 5625
  20. 399
  21. 4489
  22. 64
  23. 9
  24. 4
  25. 836
  26. 65
  27. 144
  28. 7225
  29. 20
  30. 109
  31. 8464
  32. 6391
  33. 1536
  34. 12
  35. 6776
  36. 3969
  37. 2304
  38. 400
  39. 13
  40. 1

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