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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 929 · 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 − y² when x = 4 and y = 2.
  2. 2.Use (a − b)² = a² − 2ab + b² to find 28².
  3. 3.If a + b = 8 and ab = 12, what is a² + b²?
  4. 4.Use (a − b)² = a² − 2ab + b² to find 38².
  5. 5.Use (a + b)(a − b) = a² − b² to find 91 × 89.
  6. 6.Use (a + b)(a − b) = a² − b² to find 34 × 26.
  7. 7.If a + b = 6 and ab = 5, what is a² + b²?
  8. 8.Find the value of x² − 2xy + y² when x = 6 and y = 1.
  9. 9.Find the value of x² − y² when x = 5 and y = 4.
  10. 10.Use a² − b² = (a + b)(a − b) to find 63² − 58².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 55².
  12. 12.If a + b = 3 and ab = 2, what is a² + b²?
  13. 13.If a + b = 14 and ab = 33, what is a² + b²?
  14. 14.Use (a − b)² = a² − 2ab + b² to find 18².
  15. 15.Use (a + b)(a − b) = a² − b² to find 54 × 46.
  16. 16.If a + b = 10 and ab = 24, what is a² + b²?
  17. 17.Use (a − b)² = a² − 2ab + b² to find 75².
  18. 18.If a + b = 9 and ab = 14, what is a² + b²?
  19. 19.Use (a − b)² = a² − 2ab + b² to find 79².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 59².
  21. 21.Use (a + b)² = a² + 2ab + b² to find 24².
  22. 22.Use (a + b)² = a² + 2ab + b² to find 76².
  23. 23.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  24. 24.Find the value of x² − y² when x = 3 and y = 2.
  25. 25.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  26. 26.Use (a + b)² = a² + 2ab + b² to find 81².
  27. 27.Use a² − b² = (a + b)(a − b) to find 62² − 59².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 91².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 71².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 21².
  31. 31.Use (a − b)² = a² − 2ab + b² to find 29².
  32. 32.Use a² − b² = (a + b)(a − b) to find 40² − 6².
  33. 33.If a − b = 5 and ab = 24, what is a² + b²?
  34. 34.Use (a + b)² = a² + 2ab + b² to find 94².
  35. 35.Use a² − b² = (a + b)(a − b) to find 63² − 32².
  36. 36.Find the value of x² − 2xy + y² when x = 6 and y = 2.
  37. 37.Find the value of x² + 2xy + y² when x = 5 and y = 2.
  38. 38.Use (a + b)² = a² + 2ab + b² to find 51².
  39. 39.Use a² − b² = (a + b)(a − b) to find 27² − 22².
  40. 40.If a − b = 5 and ab = 6, what is a² + b²?

Answer key

  1. 12
  2. 784
  3. 40
  4. 1444
  5. 8099
  6. 884
  7. 26
  8. 25
  9. 9
  10. 605
  11. 3025
  12. 5
  13. 130
  14. 324
  15. 2484
  16. 52
  17. 5625
  18. 53
  19. 6241
  20. 3481
  21. 576
  22. 5776
  23. 875
  24. 5
  25. 1591
  26. 6561
  27. 363
  28. 8281
  29. 5041
  30. 441
  31. 841
  32. 1564
  33. 73
  34. 8836
  35. 2945
  36. 16
  37. 49
  38. 2601
  39. 245
  40. 37

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