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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 240 · 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 63².
  2. 2.Use a² − b² = (a + b)(a − b) to find 45² − 13².
  3. 3.Use a² − b² = (a + b)(a − b) to find 76² − 1².
  4. 4.If a − b = 4 and ab = 5, what is a² + b²?
  5. 5.If a + b = 3 and ab = 2, what is a² + b²?
  6. 6.Use a² − b² = (a + b)(a − b) to find 64² − 48².
  7. 7.Use (a − b)² = a² − 2ab + b² to find 45².
  8. 8.Find the value of x² − y² when x = 6 and y = 2.
  9. 9.Find the value of x² − y² when x = 8 and y = 5.
  10. 10.Use (a + b)² = a² + 2ab + b² to find 91².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 56².
  12. 12.Find the value of x² + 2xy + y² when x = 10 and y = 1.
  13. 13.Find the value of x² − y² when x = 7 and y = 2.
  14. 14.If a − b = 6 and ab = 27, what is a² + b²?
  15. 15.Use (a + b)² = a² + 2ab + b² to find 58².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 42².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 28².
  18. 18.Find the value of x² − y² when x = 3 and y = 2.
  19. 19.Use a² − b² = (a + b)(a − b) to find 36² − 27².
  20. 20.If a + b = 10 and ab = 24, what is a² + b²?
  21. 21.Use (a − b)² = a² − 2ab + b² to find 38².
  22. 22.Find the value of x² + 2xy + y² when x = 12 and y = 6.
  23. 23.Use (a + b)(a − b) = a² − b² to find 41 × 39.
  24. 24.If a − b = 8 and ab = 9, what is a² + b²?
  25. 25.Use (a + b)² = a² + 2ab + b² to find 102².
  26. 26.Find the value of x² − 2xy + y² when x = 12 and y = 2.
  27. 27.Use (a − b)² = a² − 2ab + b² to find 41².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 72².
  29. 29.Use (a − b)² = a² − 2ab + b² to find 67².
  30. 30.Use (a + b)(a − b) = a² − b² to find 89 × 71.
  31. 31.Use a² − b² = (a + b)(a − b) to find 73² − 10².
  32. 32.Use (a + b)² = a² + 2ab + b² to find 56².
  33. 33.Use (a + b)(a − b) = a² − b² to find 42 × 38.
  34. 34.Find the value of x² + 2xy + y² when x = 7 and y = 6.
  35. 35.If a − b = 2 and ab = 80, what is a² + b²?
  36. 36.Use (a − b)² = a² − 2ab + b² to find 44².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 16².
  38. 38.Use (a + b)(a − b) = a² − b² to find 81 × 79.
  39. 39.Use (a − b)² = a² − 2ab + b² to find 39².
  40. 40.Find the value of x² + 2xy + y² when x = 14 and y = 2.

Answer key

  1. 3969
  2. 1856
  3. 5775
  4. 26
  5. 5
  6. 1792
  7. 2025
  8. 32
  9. 39
  10. 8281
  11. 3136
  12. 121
  13. 45
  14. 90
  15. 3364
  16. 1764
  17. 784
  18. 5
  19. 567
  20. 52
  21. 1444
  22. 324
  23. 1599
  24. 82
  25. 10404
  26. 100
  27. 1681
  28. 5184
  29. 4489
  30. 6319
  31. 5229
  32. 3136
  33. 1596
  34. 169
  35. 164
  36. 1936
  37. 256
  38. 6399
  39. 1521
  40. 256

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