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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 288 · 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 91 × 89.
  2. 2.Use (a − b)² = a² − 2ab + b² to find 53².
  3. 3.Use (a + b)(a − b) = a² − b² to find 105 × 95.
  4. 4.If a + b = 14 and ab = 33, what is a² + b²?
  5. 5.Use (a − b)² = a² − 2ab + b² to find 57².
  6. 6.Use (a + b)(a − b) = a² − b² to find 69 × 51.
  7. 7.Use (a − b)² = a² − 2ab + b² to find 71².
  8. 8.Use (a + b)(a − b) = a² − b² to find 34 × 26.
  9. 9.Use (a + b)(a − b) = a² − b² to find 61 × 59.
  10. 10.If a − b = 1 and ab = 2, what is a² + b²?
  11. 11.Use a² − b² = (a + b)(a − b) to find 63² − 25².
  12. 12.Use a² − b² = (a + b)(a − b) to find 33² − 10².
  13. 13.Find the value of x² − y² when x = 15 and y = 8.
  14. 14.Use (a + b)² = a² + 2ab + b² to find 22².
  15. 15.If a + b = 6 and ab = 5, what is a² + b²?
  16. 16.Use a² − b² = (a + b)(a − b) to find 97² − 80².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 105².
  18. 18.Find the value of x² − 2xy + y² when x = 3 and y = 1.
  19. 19.Use (a − b)² = a² − 2ab + b² to find 35².
  20. 20.If a − b = 4 and ab = 5, what is a² + b²?
  21. 21.Use (a + b)(a − b) = a² − b² to find 29 × 11.
  22. 22.Find the value of x² − y² when x = 14 and y = 12.
  23. 23.Use a² − b² = (a + b)(a − b) to find 85² − 38².
  24. 24.If a + b = 13 and ab = 40, what is a² + b²?
  25. 25.Use (a + b)(a − b) = a² − b² to find 95 × 85.
  26. 26.If a + b = 4 and ab = 3, what is a² + b²?
  27. 27.Use (a + b)² = a² + 2ab + b² to find 52².
  28. 28.Use (a − b)² = a² − 2ab + b² to find 67².
  29. 29.Use a² − b² = (a + b)(a − b) to find 39² − 14².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 69².
  31. 31.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  32. 32.Find the value of x² + 2xy + y² when x = 4 and y = 2.
  33. 33.Use (a + b)² = a² + 2ab + b² to find 32².
  34. 34.Use (a − b)² = a² − 2ab + b² to find 51².
  35. 35.Use (a + b)² = a² + 2ab + b² to find 63².
  36. 36.Use a² − b² = (a + b)(a − b) to find 83² − 47².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 15².
  38. 38.Find the value of x² − 2xy + y² when x = 15 and y = 10.
  39. 39.Use (a + b)(a − b) = a² − b² to find 82 × 78.
  40. 40.Use (a + b)(a − b) = a² − b² to find 94 × 86.

Answer key

  1. 8099
  2. 2809
  3. 9975
  4. 130
  5. 3249
  6. 3519
  7. 5041
  8. 884
  9. 3599
  10. 5
  11. 3344
  12. 989
  13. 161
  14. 484
  15. 26
  16. 3009
  17. 11025
  18. 4
  19. 1225
  20. 26
  21. 319
  22. 52
  23. 5781
  24. 89
  25. 8075
  26. 10
  27. 2704
  28. 4489
  29. 1325
  30. 4761
  31. 1591
  32. 36
  33. 1024
  34. 2601
  35. 3969
  36. 4680
  37. 225
  38. 25
  39. 6396
  40. 8084

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