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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 53 · 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 49².
  2. 2.Use a² − b² = (a + b)(a − b) to find 20² − 1².
  3. 3.Find the value of x² + 2xy + y² when x = 10 and y = 1.
  4. 4.Use a² − b² = (a + b)(a − b) to find 96² − 1².
  5. 5.Use (a + b)(a − b) = a² − b² to find 98 × 82.
  6. 6.Use (a + b)² = a² + 2ab + b² to find 95².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 93².
  8. 8.If a + b = 6 and ab = 5, what is a² + b²?
  9. 9.Use a² − b² = (a + b)(a − b) to find 91² − 48².
  10. 10.Use a² − b² = (a + b)(a − b) to find 85² − 7².
  11. 11.Use (a + b)² = a² + 2ab + b² to find 19².
  12. 12.Use (a + b)(a − b) = a² − b² to find 36 × 24.
  13. 13.Use (a + b)² = a² + 2ab + b² to find 106².
  14. 14.If a + b = 15 and ab = 36, what is a² + b²?
  15. 15.Use (a + b)(a − b) = a² − b² to find 63 × 57.
  16. 16.Use (a − b)² = a² − 2ab + b² to find 97².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 26².
  18. 18.Use (a + b)² = a² + 2ab + b² to find 13².
  19. 19.Use a² − b² = (a + b)(a − b) to find 95² − 77².
  20. 20.Use (a + b)² = a² + 2ab + b² to find 101².
  21. 21.If a − b = 2 and ab = 15, what is a² + b²?
  22. 22.Find the value of x² − y² when x = 5 and y = 1.
  23. 23.Use a² − b² = (a + b)(a − b) to find 97² − 69².
  24. 24.Use (a − b)² = a² − 2ab + b² to find 52².
  25. 25.Use a² − b² = (a + b)(a − b) to find 47² − 32².
  26. 26.If a − b = 10 and ab = 11, what is a² + b²?
  27. 27.Find the value of x² + 2xy + y² when x = 3 and y = 1.
  28. 28.Find the value of x² + 2xy + y² when x = 12 and y = 1.
  29. 29.Use a² − b² = (a + b)(a − b) to find 40² − 15².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 84².
  31. 31.Find the value of x² + 2xy + y² when x = 4 and y = 1.
  32. 32.Use (a − b)² = a² − 2ab + b² to find 16².
  33. 33.Use (a − b)² = a² − 2ab + b² to find 35².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 11².
  35. 35.Use (a + b)(a − b) = a² − b² to find 49 × 31.
  36. 36.Find the value of x² − 2xy + y² when x = 9 and y = 2.
  37. 37.If a − b = 8 and ab = 9, what is a² + b²?
  38. 38.Find the value of x² + 2xy + y² when x = 13 and y = 8.
  39. 39.Use a² − b² = (a + b)(a − b) to find 95² − 4².
  40. 40.Use (a − b)² = a² − 2ab + b² to find 23².

Answer key

  1. 2401
  2. 399
  3. 121
  4. 9215
  5. 8036
  6. 9025
  7. 8649
  8. 26
  9. 5977
  10. 7176
  11. 361
  12. 864
  13. 11236
  14. 153
  15. 3591
  16. 9409
  17. 676
  18. 169
  19. 3096
  20. 10201
  21. 34
  22. 24
  23. 4648
  24. 2704
  25. 1185
  26. 122
  27. 16
  28. 169
  29. 1375
  30. 7056
  31. 25
  32. 256
  33. 1225
  34. 121
  35. 1519
  36. 49
  37. 82
  38. 441
  39. 9009
  40. 529

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