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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 131 · 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 46².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 105².
  3. 3.Use a² − b² = (a + b)(a − b) to find 43² − 6².
  4. 4.Use (a + b)(a − b) = a² − b² to find 78 × 62.
  5. 5.If a + b = 22 and ab = 120, what is a² + b²?
  6. 6.If a + b = 18 and ab = 80, what is a² + b²?
  7. 7.Use (a − b)² = a² − 2ab + b² to find 56².
  8. 8.If a − b = 1 and ab = 6, what is a² + b²?
  9. 9.Find the value of x² − y² when x = 6 and y = 4.
  10. 10.Use (a − b)² = a² − 2ab + b² to find 49².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 27².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 43².
  13. 13.Use (a − b)² = a² − 2ab + b² to find 69².
  14. 14.Use (a − b)² = a² − 2ab + b² to find 58².
  15. 15.Use (a + b)(a − b) = a² − b² to find 28 × 12.
  16. 16.Find the value of x² − y² when x = 13 and y = 3.
  17. 17.Use (a + b)² = a² + 2ab + b² to find 75².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 67².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 26².
  20. 20.Use (a + b)² = a² + 2ab + b² to find 32².
  21. 21.Use a² − b² = (a + b)(a − b) to find 99² − 34².
  22. 22.Find the value of x² − y² when x = 9 and y = 5.
  23. 23.Use (a + b)² = a² + 2ab + b² to find 48².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 65².
  25. 25.Use (a + b)² = a² + 2ab + b² to find 19².
  26. 26.Use (a + b)(a − b) = a² − b² to find 91 × 89.
  27. 27.Use a² − b² = (a + b)(a − b) to find 38² − 12².
  28. 28.Use a² − b² = (a + b)(a − b) to find 86² − 23².
  29. 29.If a − b = 1 and ab = 2, what is a² + b²?
  30. 30.Use a² − b² = (a + b)(a − b) to find 70² − 58².
  31. 31.If a − b = 6 and ab = 16, what is a² + b²?
  32. 32.Use (a + b)² = a² + 2ab + b² to find 95².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 12².
  34. 34.If a − b = 2 and ab = 3, what is a² + b²?
  35. 35.Find the value of x² + 2xy + y² when x = 13 and y = 4.
  36. 36.Use (a + b)² = a² + 2ab + b² to find 25².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 57².
  38. 38.If a + b = 15 and ab = 50, what is a² + b²?
  39. 39.Use (a + b)² = a² + 2ab + b² to find 37².
  40. 40.Use (a − b)² = a² − 2ab + b² to find 53².

Answer key

  1. 2116
  2. 11025
  3. 1813
  4. 4836
  5. 244
  6. 164
  7. 3136
  8. 13
  9. 20
  10. 2401
  11. 729
  12. 1849
  13. 4761
  14. 3364
  15. 336
  16. 160
  17. 5625
  18. 4489
  19. 676
  20. 1024
  21. 8645
  22. 56
  23. 2304
  24. 4225
  25. 361
  26. 8099
  27. 1300
  28. 6867
  29. 5
  30. 1536
  31. 68
  32. 9025
  33. 144
  34. 10
  35. 289
  36. 625
  37. 3249
  38. 125
  39. 1369
  40. 2809

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