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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 423 · 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 13².
  2. 2.If a + b = 4 and ab = 3, what is a² + b²?
  3. 3.Use (a − b)² = a² − 2ab + b² to find 39².
  4. 4.Use a² − b² = (a + b)(a − b) to find 78² − 52².
  5. 5.Use (a + b)² = a² + 2ab + b² to find 26².
  6. 6.Find the value of x² + 2xy + y² when x = 7 and y = 4.
  7. 7.If a + b = 18 and ab = 80, what is a² + b²?
  8. 8.Use (a + b)(a − b) = a² − b² to find 36 × 24.
  9. 9.Find the value of x² + 2xy + y² when x = 10 and y = 9.
  10. 10.If a + b = 8 and ab = 12, what is a² + b²?
  11. 11.Use a² − b² = (a + b)(a − b) to find 45² − 2².
  12. 12.Use (a + b)² = a² + 2ab + b² to find 92².
  13. 13.Use a² − b² = (a + b)(a − b) to find 28² − 14².
  14. 14.Use (a − b)² = a² − 2ab + b² to find 31².
  15. 15.Find the value of x² − y² when x = 4 and y = 2.
  16. 16.Use (a − b)² = a² − 2ab + b² to find 49².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 103².
  18. 18.Use a² − b² = (a + b)(a − b) to find 57² − 46².
  19. 19.If a − b = 1 and ab = 132, what is a² + b²?
  20. 20.Use (a + b)² = a² + 2ab + b² to find 105².
  21. 21.Use (a + b)² = a² + 2ab + b² to find 58².
  22. 22.Find the value of x² − y² when x = 14 and y = 7.
  23. 23.Use a² − b² = (a + b)(a − b) to find 43² − 3².
  24. 24.Use a² − b² = (a + b)(a − b) to find 64² − 42².
  25. 25.Use (a + b)² = a² + 2ab + b² to find 49².
  26. 26.Use (a + b)² = a² + 2ab + b² to find 11².
  27. 27.If a − b = 1 and ab = 6, what is a² + b²?
  28. 28.Use (a + b)² = a² + 2ab + b² to find 13².
  29. 29.Find the value of x² − y² when x = 15 and y = 4.
  30. 30.Use (a + b)² = a² + 2ab + b² to find 32².
  31. 31.Use (a − b)² = a² − 2ab + b² to find 77².
  32. 32.Use (a + b)² = a² + 2ab + b² to find 24².
  33. 33.Use (a − b)² = a² − 2ab + b² to find 16².
  34. 34.If a − b = 6 and ab = 27, what is a² + b²?
  35. 35.Find the value of x² + 2xy + y² when x = 11 and y = 5.
  36. 36.Use a² − b² = (a + b)(a − b) to find 28² − 23².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 76².
  38. 38.If a + b = 14 and ab = 48, what is a² + b²?
  39. 39.Use (a − b)² = a² − 2ab + b² to find 48².
  40. 40.Find the value of x² + 2xy + y² when x = 11 and y = 1.

Answer key

  1. 169
  2. 10
  3. 1521
  4. 3380
  5. 676
  6. 121
  7. 164
  8. 864
  9. 361
  10. 40
  11. 2021
  12. 8464
  13. 588
  14. 961
  15. 12
  16. 2401
  17. 10609
  18. 1133
  19. 265
  20. 11025
  21. 3364
  22. 147
  23. 1840
  24. 2332
  25. 2401
  26. 121
  27. 13
  28. 169
  29. 209
  30. 1024
  31. 5929
  32. 576
  33. 256
  34. 90
  35. 256
  36. 255
  37. 5776
  38. 100
  39. 2304
  40. 144

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