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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 712 · 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 54².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 99².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 48².
  4. 4.Use a² − b² = (a + b)(a − b) to find 81² − 37².
  5. 5.Find the value of x² − 2xy + y² when x = 3 and y = 2.
  6. 6.Use (a − b)² = a² − 2ab + b² to find 51².
  7. 7.If a + b = 4 and ab = 3, what is a² + b²?
  8. 8.Use (a − b)² = a² − 2ab + b² to find 89².
  9. 9.Use a² − b² = (a + b)(a − b) to find 57² − 19².
  10. 10.Use (a − b)² = a² − 2ab + b² to find 12².
  11. 11.Use (a + b)(a − b) = a² − b² to find 42 × 38.
  12. 12.Use (a + b)(a − b) = a² − b² to find 98 × 82.
  13. 13.Find the value of x² + 2xy + y² when x = 9 and y = 2.
  14. 14.Use (a + b)² = a² + 2ab + b² to find 32².
  15. 15.Find the value of x² + 2xy + y² when x = 6 and y = 4.
  16. 16.If a − b = 3 and ab = 4, what is a² + b²?
  17. 17.Use (a + b)(a − b) = a² − b² to find 109 × 91.
  18. 18.Use a² − b² = (a + b)(a − b) to find 58² − 45².
  19. 19.Find the value of x² − y² when x = 7 and y = 4.
  20. 20.Use (a + b)(a − b) = a² − b² to find 84 × 76.
  21. 21.Use (a − b)² = a² − 2ab + b² to find 64².
  22. 22.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  23. 23.Use a² − b² = (a + b)(a − b) to find 62² − 26².
  24. 24.Use (a + b)(a − b) = a² − b² to find 92 × 88.
  25. 25.Use (a + b)² = a² + 2ab + b² to find 15².
  26. 26.Find the value of x² + 2xy + y² when x = 8 and y = 2.
  27. 27.Find the value of x² − y² when x = 5 and y = 4.
  28. 28.Use (a + b)(a − b) = a² − b² to find 93 × 87.
  29. 29.Find the value of x² − y² when x = 4 and y = 3.
  30. 30.Find the value of x² + 2xy + y² when x = 13 and y = 3.
  31. 31.If a − b = 2 and ab = 3, what is a² + b²?
  32. 32.Find the value of x² − 2xy + y² when x = 10 and y = 9.
  33. 33.Use (a + b)² = a² + 2ab + b² to find 63².
  34. 34.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  35. 35.Find the value of x² − 2xy + y² when x = 14 and y = 3.
  36. 36.Use (a + b)² = a² + 2ab + b² to find 41².
  37. 37.Use a² − b² = (a + b)(a − b) to find 46² − 8².
  38. 38.Use (a + b)² = a² + 2ab + b² to find 21².
  39. 39.Find the value of x² − y² when x = 5 and y = 1.
  40. 40.Use (a + b)² = a² + 2ab + b² to find 71².

Answer key

  1. 2916
  2. 9801
  3. 2304
  4. 5192
  5. 1
  6. 2601
  7. 10
  8. 7921
  9. 2888
  10. 144
  11. 1596
  12. 8036
  13. 121
  14. 1024
  15. 100
  16. 17
  17. 9919
  18. 1339
  19. 33
  20. 6384
  21. 4096
  22. 875
  23. 3168
  24. 8096
  25. 225
  26. 100
  27. 9
  28. 8091
  29. 7
  30. 256
  31. 10
  32. 1
  33. 3969
  34. 899
  35. 121
  36. 1681
  37. 2052
  38. 441
  39. 24
  40. 5041

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