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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 62 · 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 75².
  2. 2.Find the value of x² − y² when x = 12 and y = 6.
  3. 3.Find the value of x² − 2xy + y² when x = 8 and y = 7.
  4. 4.Use a² − b² = (a + b)(a − b) to find 25² − 24².
  5. 5.If a + b = 7 and ab = 12, what is a² + b²?
  6. 6.Use (a − b)² = a² − 2ab + b² to find 87².
  7. 7.Use (a + b)(a − b) = a² − b² to find 101 × 99.
  8. 8.Use (a + b)² = a² + 2ab + b² to find 22².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 32².
  10. 10.Use (a − b)² = a² − 2ab + b² to find 44².
  11. 11.Use (a + b)(a − b) = a² − b² to find 45 × 35.
  12. 12.Use (a − b)² = a² − 2ab + b² to find 56².
  13. 13.Use (a − b)² = a² − 2ab + b² to find 48².
  14. 14.Find the value of x² − y² when x = 6 and y = 1.
  15. 15.Use (a + b)² = a² + 2ab + b² to find 31².
  16. 16.Use (a + b)(a − b) = a² − b² to find 92 × 88.
  17. 17.Use a² − b² = (a + b)(a − b) to find 46² − 38².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 84².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 63².
  20. 20.Find the value of x² − 2xy + y² when x = 6 and y = 5.
  21. 21.Use a² − b² = (a + b)(a − b) to find 45² − 39².
  22. 22.Use a² − b² = (a + b)(a − b) to find 84² − 14².
  23. 23.Use (a + b)² = a² + 2ab + b² to find 83².
  24. 24.Use (a − b)² = a² − 2ab + b² to find 38².
  25. 25.If a + b = 3 and ab = 2, what is a² + b²?
  26. 26.Use (a − b)² = a² − 2ab + b² to find 65².
  27. 27.Use (a + b)² = a² + 2ab + b² to find 61².
  28. 28.Use (a + b)(a − b) = a² − b² to find 104 × 96.
  29. 29.Use a² − b² = (a + b)(a − b) to find 48² − 11².
  30. 30.Find the value of x² − y² when x = 6 and y = 3.
  31. 31.Use (a + b)(a − b) = a² − b² to find 93 × 87.
  32. 32.Use a² − b² = (a + b)(a − b) to find 42² − 7².
  33. 33.Find the value of x² + 2xy + y² when x = 11 and y = 4.
  34. 34.Find the value of x² − y² when x = 13 and y = 1.
  35. 35.Use (a + b)(a − b) = a² − b² to find 49 × 31.
  36. 36.Find the value of x² + 2xy + y² when x = 10 and y = 3.
  37. 37.Use (a − b)² = a² − 2ab + b² to find 91².
  38. 38.Use (a + b)(a − b) = a² − b² to find 63 × 57.
  39. 39.Use a² − b² = (a + b)(a − b) to find 32² − 2².
  40. 40.Use (a + b)² = a² + 2ab + b² to find 45².

Answer key

  1. 5625
  2. 108
  3. 1
  4. 49
  5. 25
  6. 7569
  7. 9999
  8. 484
  9. 1024
  10. 1936
  11. 1575
  12. 3136
  13. 2304
  14. 35
  15. 961
  16. 8096
  17. 672
  18. 7056
  19. 3969
  20. 1
  21. 504
  22. 6860
  23. 6889
  24. 1444
  25. 5
  26. 4225
  27. 3721
  28. 9984
  29. 2183
  30. 27
  31. 8091
  32. 1715
  33. 225
  34. 168
  35. 1519
  36. 169
  37. 8281
  38. 3591
  39. 1020
  40. 2025

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