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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 378 · 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 98².
  2. 2.Use (a − b)² = a² − 2ab + b² to find 82².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 52².
  4. 4.If a + b = 9 and ab = 18, what is a² + b²?
  5. 5.Use (a + b)² = a² + 2ab + b² to find 77².
  6. 6.Use a² − b² = (a + b)(a − b) to find 36² − 10².
  7. 7.Use a² − b² = (a + b)(a − b) to find 48² − 26².
  8. 8.Find the value of x² + 2xy + y² when x = 15 and y = 11.
  9. 9.Use (a + b)² = a² + 2ab + b² to find 38².
  10. 10.If a − b = 7 and ab = 44, what is a² + b²?
  11. 11.Use (a − b)² = a² − 2ab + b² to find 34².
  12. 12.Use (a + b)² = a² + 2ab + b² to find 49².
  13. 13.Use (a + b)² = a² + 2ab + b² to find 37².
  14. 14.Use (a + b)² = a² + 2ab + b² to find 61².
  15. 15.Use a² − b² = (a + b)(a − b) to find 41² − 31².
  16. 16.Use (a + b)(a − b) = a² − b² to find 103 × 97.
  17. 17.Find the value of x² − y² when x = 6 and y = 5.
  18. 18.Use (a − b)² = a² − 2ab + b² to find 22².
  19. 19.Use a² − b² = (a + b)(a − b) to find 48² − 11².
  20. 20.Find the value of x² + 2xy + y² when x = 6 and y = 1.
  21. 21.Use (a + b)² = a² + 2ab + b² to find 73².
  22. 22.Find the value of x² − y² when x = 9 and y = 4.
  23. 23.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  24. 24.If a + b = 14 and ab = 24, what is a² + b²?
  25. 25.Use a² − b² = (a + b)(a − b) to find 79² − 67².
  26. 26.Use a² − b² = (a + b)(a − b) to find 22² − 12².
  27. 27.Use (a − b)² = a² − 2ab + b² to find 89².
  28. 28.Use (a − b)² = a² − 2ab + b² to find 15².
  29. 29.If a − b = 7 and ab = 8, what is a² + b²?
  30. 30.If a − b = 4 and ab = 45, what is a² + b²?
  31. 31.Use a² − b² = (a + b)(a − b) to find 46² − 12².
  32. 32.Use (a + b)² = a² + 2ab + b² to find 23².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 69².
  34. 34.If a − b = 3 and ab = 10, what is a² + b²?
  35. 35.If a − b = 2 and ab = 80, what is a² + b²?
  36. 36.Use (a + b)(a − b) = a² − b² to find 42 × 38.
  37. 37.Use (a + b)² = a² + 2ab + b² to find 52².
  38. 38.If a − b = 3 and ab = 4, what is a² + b²?
  39. 39.Find the value of x² − y² when x = 8 and y = 6.
  40. 40.Use (a + b)² = a² + 2ab + b² to find 39².

Answer key

  1. 9604
  2. 6724
  3. 2704
  4. 45
  5. 5929
  6. 1196
  7. 1628
  8. 676
  9. 1444
  10. 137
  11. 1156
  12. 2401
  13. 1369
  14. 3721
  15. 720
  16. 9991
  17. 11
  18. 484
  19. 2183
  20. 49
  21. 5329
  22. 65
  23. 875
  24. 148
  25. 1752
  26. 340
  27. 7921
  28. 225
  29. 65
  30. 106
  31. 1972
  32. 529
  33. 4761
  34. 29
  35. 164
  36. 1596
  37. 2704
  38. 17
  39. 28
  40. 1521

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