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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 426 · 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 = 14 and y = 11.
  2. 2.If a + b = 16 and ab = 48, what is a² + b²?
  3. 3.If a + b = 5 and ab = 6, what is a² + b²?
  4. 4.Use (a + b)² = a² + 2ab + b² to find 61².
  5. 5.Use (a + b)² = a² + 2ab + b² to find 39².
  6. 6.Use (a + b)(a − b) = a² − b² to find 85 × 75.
  7. 7.Find the value of x² + 2xy + y² when x = 14 and y = 2.
  8. 8.Use (a + b)(a − b) = a² − b² to find 92 × 88.
  9. 9.Use (a − b)² = a² − 2ab + b² to find 27².
  10. 10.Use a² − b² = (a + b)(a − b) to find 23² − 13².
  11. 11.Use (a + b)² = a² + 2ab + b² to find 87².
  12. 12.Use (a + b)² = a² + 2ab + b² to find 62².
  13. 13.Find the value of x² − 2xy + y² when x = 4 and y = 1.
  14. 14.Use (a + b)² = a² + 2ab + b² to find 37².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 47².
  16. 16.Use (a + b)(a − b) = a² − b² to find 96 × 84.
  17. 17.Use a² − b² = (a + b)(a − b) to find 92² − 73².
  18. 18.Find the value of x² − y² when x = 9 and y = 5.
  19. 19.Use (a + b)(a − b) = a² − b² to find 89 × 71.
  20. 20.Use (a + b)(a − b) = a² − b² to find 104 × 96.
  21. 21.Use (a − b)² = a² − 2ab + b² to find 13².
  22. 22.Use (a + b)² = a² + 2ab + b² to find 26².
  23. 23.Use a² − b² = (a + b)(a − b) to find 86² − 49².
  24. 24.Find the value of x² + 2xy + y² when x = 14 and y = 7.
  25. 25.Use a² − b² = (a + b)(a − b) to find 74² − 3².
  26. 26.Use (a − b)² = a² − 2ab + b² to find 26².
  27. 27.Use (a + b)² = a² + 2ab + b² to find 83².
  28. 28.Use (a − b)² = a² − 2ab + b² to find 84².
  29. 29.Use a² − b² = (a + b)(a − b) to find 21² − 18².
  30. 30.Find the value of x² − 2xy + y² when x = 7 and y = 4.
  31. 31.Use (a + b)(a − b) = a² − b² to find 37 × 23.
  32. 32.Use (a − b)² = a² − 2ab + b² to find 73².
  33. 33.Use (a − b)² = a² − 2ab + b² to find 67².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 18².
  35. 35.Use (a − b)² = a² − 2ab + b² to find 57².
  36. 36.Use a² − b² = (a + b)(a − b) to find 24² − 12².
  37. 37.Use (a + b)(a − b) = a² − b² to find 77 × 63.
  38. 38.Use (a + b)² = a² + 2ab + b² to find 13².
  39. 39.If a − b = 3 and ab = 40, what is a² + b²?
  40. 40.Use a² − b² = (a + b)(a − b) to find 51² − 13².

Answer key

  1. 9
  2. 160
  3. 13
  4. 3721
  5. 1521
  6. 6375
  7. 256
  8. 8096
  9. 729
  10. 360
  11. 7569
  12. 3844
  13. 9
  14. 1369
  15. 2209
  16. 8064
  17. 3135
  18. 56
  19. 6319
  20. 9984
  21. 169
  22. 676
  23. 4995
  24. 441
  25. 5467
  26. 676
  27. 6889
  28. 7056
  29. 117
  30. 9
  31. 851
  32. 5329
  33. 4489
  34. 324
  35. 3249
  36. 432
  37. 4851
  38. 169
  39. 89
  40. 2432

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