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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 888 · 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 103².
  2. 2.Use (a − b)² = a² − 2ab + b² to find 86².
  3. 3.Use a² − b² = (a + b)(a − b) to find 32² − 6².
  4. 4.Use (a − b)² = a² − 2ab + b² to find 45².
  5. 5.If a + b = 3 and ab = 2, what is a² + b²?
  6. 6.Use (a − b)² = a² − 2ab + b² to find 64².
  7. 7.Use (a + b)(a − b) = a² − b² to find 25 × 15.
  8. 8.Use (a + b)² = a² + 2ab + b² to find 43².
  9. 9.Use (a + b)(a − b) = a² − b² to find 23 × 17.
  10. 10.Use (a + b)(a − b) = a² − b² to find 58 × 42.
  11. 11.Use (a − b)² = a² − 2ab + b² to find 37².
  12. 12.Use (a + b)² = a² + 2ab + b² to find 86².
  13. 13.Use a² − b² = (a + b)(a − b) to find 87² − 51².
  14. 14.Use (a − b)² = a² − 2ab + b² to find 56².
  15. 15.Use a² − b² = (a + b)(a − b) to find 22² − 17².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 61².
  17. 17.Find the value of x² + 2xy + y² when x = 9 and y = 7.
  18. 18.Use a² − b² = (a + b)(a − b) to find 29² − 3².
  19. 19.Find the value of x² + 2xy + y² when x = 15 and y = 12.
  20. 20.Use (a + b)² = a² + 2ab + b² to find 98².
  21. 21.Find the value of x² − y² when x = 6 and y = 1.
  22. 22.If a − b = 3 and ab = 88, what is a² + b²?
  23. 23.Use (a − b)² = a² − 2ab + b² to find 22².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 87².
  25. 25.If a + b = 9 and ab = 20, what is a² + b²?
  26. 26.Use (a − b)² = a² − 2ab + b² to find 18².
  27. 27.Use a² − b² = (a + b)(a − b) to find 20² − 6².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 62².
  29. 29.Use (a + b)(a − b) = a² − b² to find 95 × 85.
  30. 30.Use a² − b² = (a + b)(a − b) to find 46² − 12².
  31. 31.Use (a + b)(a − b) = a² − b² to find 36 × 24.
  32. 32.Find the value of x² + 2xy + y² when x = 3 and y = 1.
  33. 33.Find the value of x² − y² when x = 3 and y = 2.
  34. 34.Use (a + b)² = a² + 2ab + b² to find 48².
  35. 35.Use a² − b² = (a + b)(a − b) to find 39² − 24².
  36. 36.If a + b = 15 and ab = 36, what is a² + b²?
  37. 37.If a + b = 14 and ab = 33, what is a² + b²?
  38. 38.Use (a − b)² = a² − 2ab + b² to find 82².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 12².
  40. 40.Use (a − b)² = a² − 2ab + b² to find 58².

Answer key

  1. 10609
  2. 7396
  3. 988
  4. 2025
  5. 5
  6. 4096
  7. 375
  8. 1849
  9. 391
  10. 2436
  11. 1369
  12. 7396
  13. 4968
  14. 3136
  15. 195
  16. 3721
  17. 256
  18. 832
  19. 729
  20. 9604
  21. 35
  22. 185
  23. 484
  24. 7569
  25. 41
  26. 324
  27. 364
  28. 3844
  29. 8075
  30. 1972
  31. 864
  32. 16
  33. 5
  34. 2304
  35. 945
  36. 153
  37. 130
  38. 6724
  39. 144
  40. 3364

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