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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 979 · 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)(a − b) = a² − b² to find 103 × 97.
  2. 2.Use a² − b² = (a + b)(a − b) to find 40² − 4².
  3. 3.Use (a + b)² = a² + 2ab + b² to find 95².
  4. 4.If a + b = 14 and ab = 40, what is a² + b²?
  5. 5.Use (a − b)² = a² − 2ab + b² to find 59².
  6. 6.Use (a + b)² = a² + 2ab + b² to find 59².
  7. 7.Find the value of x² + 2xy + y² when x = 14 and y = 12.
  8. 8.Use (a − b)² = a² − 2ab + b² to find 67².
  9. 9.Use (a − b)² = a² − 2ab + b² to find 28².
  10. 10.Use (a − b)² = a² − 2ab + b² to find 82².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 23².
  12. 12.Use (a + b)(a − b) = a² − b² to find 44 × 36.
  13. 13.Use (a + b)² = a² + 2ab + b² to find 39².
  14. 14.If a − b = 1 and ab = 6, what is a² + b²?
  15. 15.If a − b = 1 and ab = 72, what is a² + b²?
  16. 16.Use (a + b)² = a² + 2ab + b² to find 18².
  17. 17.Use a² − b² = (a + b)(a − b) to find 94² − 73².
  18. 18.Use (a + b)² = a² + 2ab + b² to find 24².
  19. 19.If a + b = 10 and ab = 9, what is a² + b²?
  20. 20.If a + b = 10 and ab = 21, what is a² + b²?
  21. 21.Use (a − b)² = a² − 2ab + b² to find 13².
  22. 22.Use (a + b)² = a² + 2ab + b² to find 88².
  23. 23.Use a² − b² = (a + b)(a − b) to find 28² − 1².
  24. 24.Find the value of x² − y² when x = 5 and y = 4.
  25. 25.Use (a + b)(a − b) = a² − b² to find 86 × 74.
  26. 26.Find the value of x² − y² when x = 14 and y = 11.
  27. 27.Use a² − b² = (a + b)(a − b) to find 34² − 5².
  28. 28.Use (a + b)(a − b) = a² − b² to find 52 × 48.
  29. 29.Use (a + b)(a − b) = a² − b² to find 23 × 17.
  30. 30.Use (a + b)² = a² + 2ab + b² to find 92².
  31. 31.Use (a + b)² = a² + 2ab + b² to find 71².
  32. 32.Use (a − b)² = a² − 2ab + b² to find 77².
  33. 33.Find the value of x² + 2xy + y² when x = 10 and y = 9.
  34. 34.If a + b = 6 and ab = 5, what is a² + b²?
  35. 35.Use (a + b)² = a² + 2ab + b² to find 32².
  36. 36.Find the value of x² − 2xy + y² when x = 13 and y = 8.
  37. 37.Use (a − b)² = a² − 2ab + b² to find 84².
  38. 38.Find the value of x² − y² when x = 3 and y = 2.
  39. 39.Use (a + b)² = a² + 2ab + b² to find 51².
  40. 40.Find the value of x² − 2xy + y² when x = 11 and y = 5.

Answer key

  1. 9991
  2. 1584
  3. 9025
  4. 116
  5. 3481
  6. 3481
  7. 676
  8. 4489
  9. 784
  10. 6724
  11. 529
  12. 1584
  13. 1521
  14. 13
  15. 145
  16. 324
  17. 3507
  18. 576
  19. 82
  20. 58
  21. 169
  22. 7744
  23. 783
  24. 9
  25. 6364
  26. 75
  27. 1131
  28. 2496
  29. 391
  30. 8464
  31. 5041
  32. 5929
  33. 361
  34. 26
  35. 1024
  36. 25
  37. 7056
  38. 5
  39. 2601
  40. 36

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