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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 5 · 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.Find the value of x² − 2xy + y² when x = 12 and y = 5.
  2. 2.Find the value of x² + 2xy + y² when x = 14 and y = 6.
  3. 3.Use (a − b)² = a² − 2ab + b² to find 93².
  4. 4.Use (a + b)² = a² + 2ab + b² to find 105².
  5. 5.Use (a + b)(a − b) = a² − b² to find 56 × 44.
  6. 6.Use (a − b)² = a² − 2ab + b² to find 15².
  7. 7.Find the value of x² − y² when x = 12 and y = 7.
  8. 8.Use a² − b² = (a + b)(a − b) to find 75² − 34².
  9. 9.Use (a + b)(a − b) = a² − b² to find 95 × 85.
  10. 10.Use (a − b)² = a² − 2ab + b² to find 43².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 53².
  12. 12.Use a² − b² = (a + b)(a − b) to find 46² − 38².
  13. 13.If a + b = 7 and ab = 6, what is a² + b²?
  14. 14.Use (a + b)(a − b) = a² − b² to find 25 × 15.
  15. 15.Use (a + b)(a − b) = a² − b² to find 102 × 98.
  16. 16.If a + b = 11 and ab = 18, what is a² + b²?
  17. 17.Use (a − b)² = a² − 2ab + b² to find 32².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 14².
  19. 19.Find the value of x² + 2xy + y² when x = 9 and y = 6.
  20. 20.Use (a + b)(a − b) = a² − b² to find 38 × 22.
  21. 21.Find the value of x² − y² when x = 4 and y = 2.
  22. 22.If a + b = 3 and ab = 2, what is a² + b²?
  23. 23.Use a² − b² = (a + b)(a − b) to find 87² − 38².
  24. 24.Use (a − b)² = a² − 2ab + b² to find 16².
  25. 25.Find the value of x² − 2xy + y² when x = 6 and y = 1.
  26. 26.Use (a − b)² = a² − 2ab + b² to find 57².
  27. 27.Find the value of x² + 2xy + y² when x = 14 and y = 2.
  28. 28.If a + b = 9 and ab = 14, what is a² + b²?
  29. 29.If a + b = 12 and ab = 11, what is a² + b²?
  30. 30.Find the value of x² − y² when x = 7 and y = 6.
  31. 31.Use (a + b)² = a² + 2ab + b² to find 93².
  32. 32.Use (a + b)² = a² + 2ab + b² to find 99².
  33. 33.If a − b = 2 and ab = 3, what is a² + b²?
  34. 34.Use (a + b)² = a² + 2ab + b² to find 68².
  35. 35.If a + b = 19 and ab = 90, what is a² + b²?
  36. 36.Use a² − b² = (a + b)(a − b) to find 97² − 35².
  37. 37.Find the value of x² + 2xy + y² when x = 7 and y = 6.
  38. 38.Use (a + b)(a − b) = a² − b² to find 49 × 31.
  39. 39.If a + b = 15 and ab = 54, what is a² + b²?
  40. 40.Use a² − b² = (a + b)(a − b) to find 98² − 18².

Answer key

  1. 49
  2. 400
  3. 8649
  4. 11025
  5. 2464
  6. 225
  7. 95
  8. 4469
  9. 8075
  10. 1849
  11. 2809
  12. 672
  13. 37
  14. 375
  15. 9996
  16. 85
  17. 1024
  18. 196
  19. 225
  20. 836
  21. 12
  22. 5
  23. 6125
  24. 256
  25. 25
  26. 3249
  27. 256
  28. 53
  29. 122
  30. 13
  31. 8649
  32. 9801
  33. 10
  34. 4624
  35. 181
  36. 8184
  37. 169
  38. 1519
  39. 117
  40. 9280

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