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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 708 · 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 31².
  2. 2.If a − b = 1 and ab = 12, what is a² + b²?
  3. 3.Find the value of x² + 2xy + y² when x = 9 and y = 1.
  4. 4.Find the value of x² − y² when x = 15 and y = 1.
  5. 5.Find the value of x² − y² when x = 5 and y = 1.
  6. 6.Find the value of x² − 2xy + y² when x = 4 and y = 1.
  7. 7.Use (a − b)² = a² − 2ab + b² to find 37².
  8. 8.Use (a − b)² = a² − 2ab + b² to find 58².
  9. 9.Use (a + b)(a − b) = a² − b² to find 55 × 45.
  10. 10.Use (a + b)² = a² + 2ab + b² to find 102².
  11. 11.If a + b = 22 and ab = 120, what is a² + b²?
  12. 12.Use a² − b² = (a + b)(a − b) to find 43² − 38².
  13. 13.If a + b = 6 and ab = 5, what is a² + b²?
  14. 14.If a + b = 4 and ab = 3, what is a² + b²?
  15. 15.If a + b = 5 and ab = 4, what is a² + b²?
  16. 16.Use (a + b)² = a² + 2ab + b² to find 57².
  17. 17.Find the value of x² + 2xy + y² when x = 6 and y = 3.
  18. 18.Use a² − b² = (a + b)(a − b) to find 89² − 8².
  19. 19.If a − b = 4 and ab = 32, what is a² + b²?
  20. 20.Use (a − b)² = a² − 2ab + b² to find 68².
  21. 21.Find the value of x² − y² when x = 6 and y = 5.
  22. 22.Use (a + b)² = a² + 2ab + b² to find 96².
  23. 23.Find the value of x² − 2xy + y² when x = 9 and y = 4.
  24. 24.Use (a + b)² = a² + 2ab + b² to find 63².
  25. 25.Use (a − b)² = a² − 2ab + b² to find 11².
  26. 26.Use a² − b² = (a + b)(a − b) to find 51² − 2².
  27. 27.Use (a + b)² = a² + 2ab + b² to find 11².
  28. 28.Use a² − b² = (a + b)(a − b) to find 96² − 12².
  29. 29.Use (a − b)² = a² − 2ab + b² to find 17².
  30. 30.Use a² − b² = (a + b)(a − b) to find 33² − 6².
  31. 31.Use (a − b)² = a² − 2ab + b² to find 29².
  32. 32.If a − b = 2 and ab = 15, what is a² + b²?
  33. 33.Find the value of x² − y² when x = 10 and y = 1.
  34. 34.Find the value of x² + 2xy + y² when x = 7 and y = 2.
  35. 35.If a + b = 8 and ab = 15, what is a² + b²?
  36. 36.Use (a − b)² = a² − 2ab + b² to find 56².
  37. 37.Use (a + b)(a − b) = a² − b² to find 45 × 35.
  38. 38.Find the value of x² − y² when x = 13 and y = 11.
  39. 39.Use (a − b)² = a² − 2ab + b² to find 31².
  40. 40.If a − b = 1 and ab = 6, what is a² + b²?

Answer key

  1. 961
  2. 25
  3. 100
  4. 224
  5. 24
  6. 9
  7. 1369
  8. 3364
  9. 2475
  10. 10404
  11. 244
  12. 405
  13. 26
  14. 10
  15. 17
  16. 3249
  17. 81
  18. 7857
  19. 80
  20. 4624
  21. 11
  22. 9216
  23. 25
  24. 3969
  25. 121
  26. 2597
  27. 121
  28. 9072
  29. 289
  30. 1053
  31. 841
  32. 34
  33. 99
  34. 81
  35. 34
  36. 3136
  37. 1575
  38. 48
  39. 961
  40. 13

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