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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 647 · 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.If a + b = 5 and ab = 6, what is a² + b²?
  2. 2.If a + b = 22 and ab = 120, what is a² + b²?
  3. 3.Use (a − b)² = a² − 2ab + b² to find 32².
  4. 4.If a + b = 15 and ab = 36, what is a² + b²?
  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 68².
  7. 7.If a − b = 10 and ab = 11, what is a² + b²?
  8. 8.Use (a − b)² = a² − 2ab + b² to find 27².
  9. 9.Use a² − b² = (a + b)(a − b) to find 98² − 3².
  10. 10.Use (a − b)² = a² − 2ab + b² to find 56².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 62².
  12. 12.If a + b = 10 and ab = 16, what is a² + b²?
  13. 13.If a + b = 15 and ab = 50, what is a² + b²?
  14. 14.Find the value of x² − y² when x = 11 and y = 1.
  15. 15.Use a² − b² = (a + b)(a − b) to find 47² − 12².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 21².
  17. 17.Find the value of x² − y² when x = 6 and y = 1.
  18. 18.Use (a + b)² = a² + 2ab + b² to find 39².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 13².
  20. 20.If a + b = 18 and ab = 72, what is a² + b²?
  21. 21.If a + b = 8 and ab = 7, what is a² + b²?
  22. 22.Use (a − b)² = a² − 2ab + b² to find 21².
  23. 23.Use (a + b)² = a² + 2ab + b² to find 61².
  24. 24.Find the value of x² − y² when x = 11 and y = 10.
  25. 25.Use (a − b)² = a² − 2ab + b² to find 83².
  26. 26.Use a² − b² = (a + b)(a − b) to find 71² − 52².
  27. 27.If a + b = 8 and ab = 12, what is a² + b²?
  28. 28.Use a² − b² = (a + b)(a − b) to find 53² − 33².
  29. 29.Find the value of x² − y² when x = 11 and y = 6.
  30. 30.Use (a − b)² = a² − 2ab + b² to find 14².
  31. 31.If a − b = 2 and ab = 3, what is a² + b²?
  32. 32.Use (a + b)(a − b) = a² − b² to find 63 × 57.
  33. 33.Use (a + b)(a − b) = a² − b² to find 74 × 66.
  34. 34.If a + b = 20 and ab = 96, what is a² + b²?
  35. 35.If a − b = 3 and ab = 88, what is a² + b²?
  36. 36.Find the value of x² − y² when x = 10 and y = 6.
  37. 37.Find the value of x² − 2xy + y² when x = 9 and y = 3.
  38. 38.Use (a + b)² = a² + 2ab + b² to find 55².
  39. 39.Use (a + b)(a − b) = a² − b² to find 94 × 86.
  40. 40.If a + b = 10 and ab = 9, what is a² + b²?

Answer key

  1. 13
  2. 244
  3. 1024
  4. 153
  5. 1
  6. 4624
  7. 122
  8. 729
  9. 9595
  10. 3136
  11. 3844
  12. 68
  13. 125
  14. 120
  15. 2065
  16. 441
  17. 35
  18. 1521
  19. 169
  20. 180
  21. 50
  22. 441
  23. 3721
  24. 21
  25. 6889
  26. 2337
  27. 40
  28. 1720
  29. 85
  30. 196
  31. 10
  32. 3591
  33. 4884
  34. 208
  35. 185
  36. 64
  37. 36
  38. 3025
  39. 8084
  40. 82

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