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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 152 · 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 = 3 and y = 1.
  2. 2.Find the value of x² + 2xy + y² when x = 10 and y = 7.
  3. 3.If a − b = 1 and ab = 30, what is a² + b²?
  4. 4.If a − b = 1 and ab = 42, what is a² + b²?
  5. 5.If a + b = 3 and ab = 2, what is a² + b²?
  6. 6.If a + b = 5 and ab = 4, what is a² + b²?
  7. 7.If a + b = 9 and ab = 20, what is a² + b²?
  8. 8.Find the value of x² − y² when x = 8 and y = 7.
  9. 9.Use (a − b)² = a² − 2ab + b² to find 27².
  10. 10.Use a² − b² = (a + b)(a − b) to find 58² − 14².
  11. 11.Use (a + b)² = a² + 2ab + b² to find 53².
  12. 12.Use (a + b)² = a² + 2ab + b² to find 47².
  13. 13.Find the value of x² − y² when x = 10 and y = 3.
  14. 14.Use a² − b² = (a + b)(a − b) to find 25² − 2².
  15. 15.Use (a + b)² = a² + 2ab + b² to find 38².
  16. 16.Find the value of x² − 2xy + y² when x = 9 and y = 2.
  17. 17.Use (a + b)² = a² + 2ab + b² to find 98².
  18. 18.If a + b = 14 and ab = 33, what is a² + b²?
  19. 19.Use (a − b)² = a² − 2ab + b² to find 55².
  20. 20.Use (a + b)² = a² + 2ab + b² to find 14².
  21. 21.Use a² − b² = (a + b)(a − b) to find 53² − 52².
  22. 22.Use (a + b)² = a² + 2ab + b² to find 54².
  23. 23.Use a² − b² = (a + b)(a − b) to find 65² − 14².
  24. 24.If a + b = 7 and ab = 12, what is a² + b²?
  25. 25.Use (a − b)² = a² − 2ab + b² to find 47².
  26. 26.Use (a + b)² = a² + 2ab + b² to find 25².
  27. 27.Use (a + b)(a − b) = a² − b² to find 97 × 83.
  28. 28.Use (a + b)(a − b) = a² − b² to find 102 × 98.
  29. 29.Find the value of x² − y² when x = 7 and y = 6.
  30. 30.Use (a + b)(a − b) = a² − b² to find 36 × 24.
  31. 31.Use (a + b)(a − b) = a² − b² to find 104 × 96.
  32. 32.Find the value of x² + 2xy + y² when x = 5 and y = 3.
  33. 33.Find the value of x² − y² when x = 12 and y = 8.
  34. 34.If a − b = 3 and ab = 10, what is a² + b²?
  35. 35.Use (a − b)² = a² − 2ab + b² to find 69².
  36. 36.Use (a + b)² = a² + 2ab + b² to find 105².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 74².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 19².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 108².
  40. 40.Find the value of x² + 2xy + y² when x = 13 and y = 10.

Answer key

  1. 16
  2. 289
  3. 61
  4. 85
  5. 5
  6. 17
  7. 41
  8. 15
  9. 729
  10. 3168
  11. 2809
  12. 2209
  13. 91
  14. 621
  15. 1444
  16. 49
  17. 9604
  18. 130
  19. 3025
  20. 196
  21. 105
  22. 2916
  23. 4029
  24. 25
  25. 2209
  26. 625
  27. 8051
  28. 9996
  29. 13
  30. 864
  31. 9984
  32. 64
  33. 80
  34. 29
  35. 4761
  36. 11025
  37. 5476
  38. 361
  39. 11664
  40. 529

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