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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 451 · 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 = 12 and y = 10.
  2. 2.Use (a − b)² = a² − 2ab + b² to find 46².
  3. 3.Use (a + b)(a − b) = a² − b² to find 84 × 76.
  4. 4.Use (a + b)(a − b) = a² − b² to find 73 × 67.
  5. 5.Use (a + b)(a − b) = a² − b² to find 76 × 64.
  6. 6.Use (a + b)² = a² + 2ab + b² to find 94².
  7. 7.If a + b = 20 and ab = 99, what is a² + b²?
  8. 8.Find the value of x² − 2xy + y² when x = 6 and y = 5.
  9. 9.Find the value of x² − 2xy + y² when x = 8 and y = 1.
  10. 10.Use (a − b)² = a² − 2ab + b² to find 28².
  11. 11.Use (a + b)² = a² + 2ab + b² to find 107².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 49².
  13. 13.Use (a − b)² = a² − 2ab + b² to find 24².
  14. 14.Use (a + b)² = a² + 2ab + b² to find 55².
  15. 15.Use (a + b)² = a² + 2ab + b² to find 27².
  16. 16.If a + b = 5 and ab = 4, what is a² + b²?
  17. 17.Use (a + b)² = a² + 2ab + b² to find 32².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 27².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 16².
  20. 20.If a + b = 7 and ab = 10, what is a² + b²?
  21. 21.Use (a + b)(a − b) = a² − b² to find 95 × 85.
  22. 22.Use (a − b)² = a² − 2ab + b² to find 37².
  23. 23.Use (a + b)² = a² + 2ab + b² to find 105².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 97².
  25. 25.Use a² − b² = (a + b)(a − b) to find 25² − 12².
  26. 26.Use (a + b)(a − b) = a² − b² to find 47 × 33.
  27. 27.Use (a − b)² = a² − 2ab + b² to find 52².
  28. 28.Use (a − b)² = a² − 2ab + b² to find 48².
  29. 29.Find the value of x² + 2xy + y² when x = 10 and y = 1.
  30. 30.Find the value of x² + 2xy + y² when x = 14 and y = 4.
  31. 31.Find the value of x² − 2xy + y² when x = 11 and y = 2.
  32. 32.If a + b = 3 and ab = 2, what is a² + b²?
  33. 33.Find the value of x² − 2xy + y² when x = 12 and y = 11.
  34. 34.Use (a + b)² = a² + 2ab + b² to find 34².
  35. 35.Use (a + b)² = a² + 2ab + b² to find 92².
  36. 36.If a + b = 16 and ab = 60, what is a² + b²?
  37. 37.Use (a + b)² = a² + 2ab + b² to find 61².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 13².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 18².
  40. 40.Use (a − b)² = a² − 2ab + b² to find 33².

Answer key

  1. 484
  2. 2116
  3. 6384
  4. 4891
  5. 4864
  6. 8836
  7. 202
  8. 1
  9. 49
  10. 784
  11. 11449
  12. 2401
  13. 576
  14. 3025
  15. 729
  16. 17
  17. 1024
  18. 729
  19. 256
  20. 29
  21. 8075
  22. 1369
  23. 11025
  24. 9409
  25. 481
  26. 1551
  27. 2704
  28. 2304
  29. 121
  30. 324
  31. 81
  32. 5
  33. 1
  34. 1156
  35. 8464
  36. 136
  37. 3721
  38. 169
  39. 324
  40. 1089

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