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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 264 · 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 74².
  2. 2.If a + b = 3 and ab = 2, what is a² + b²?
  3. 3.Use a² − b² = (a + b)(a − b) to find 86² − 15².
  4. 4.If a − b = 2 and ab = 24, what is a² + b²?
  5. 5.Use a² − b² = (a + b)(a − b) to find 41² − 16².
  6. 6.If a − b = 1 and ab = 42, what is a² + b²?
  7. 7.If a − b = 7 and ab = 30, what is a² + b²?
  8. 8.Use (a + b)(a − b) = a² − b² to find 105 × 95.
  9. 9.Use (a + b)(a − b) = a² − b² to find 49 × 31.
  10. 10.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  11. 11.Use (a + b)² = a² + 2ab + b² to find 43².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 65².
  13. 13.Use a² − b² = (a + b)(a − b) to find 29² − 10².
  14. 14.Use a² − b² = (a + b)(a − b) to find 52² − 35².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 58².
  16. 16.Use (a − b)² = a² − 2ab + b² to find 43².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 72².
  18. 18.Find the value of x² − 2xy + y² when x = 5 and y = 1.
  19. 19.Use (a − b)² = a² − 2ab + b² to find 53².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 38².
  21. 21.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  22. 22.Use a² − b² = (a + b)(a − b) to find 40² − 3².
  23. 23.Use a² − b² = (a + b)(a − b) to find 74² − 71².
  24. 24.Use (a + b)(a − b) = a² − b² to find 39 × 21.
  25. 25.If a + b = 6 and ab = 5, what is a² + b²?
  26. 26.Use a² − b² = (a + b)(a − b) to find 74² − 10².
  27. 27.Use (a − b)² = a² − 2ab + b² to find 36².
  28. 28.Use (a + b)(a − b) = a² − b² to find 51 × 49.
  29. 29.Use a² − b² = (a + b)(a − b) to find 67² − 17².
  30. 30.Use a² − b² = (a + b)(a − b) to find 21² − 8².
  31. 31.If a + b = 5 and ab = 6, what is a² + b²?
  32. 32.If a − b = 10 and ab = 11, what is a² + b²?
  33. 33.Find the value of x² − 2xy + y² when x = 11 and y = 9.
  34. 34.Find the value of x² + 2xy + y² when x = 11 and y = 4.
  35. 35.Use (a − b)² = a² − 2ab + b² to find 26².
  36. 36.If a + b = 5 and ab = 4, what is a² + b²?
  37. 37.Use (a + b)(a − b) = a² − b² to find 58 × 42.
  38. 38.Use (a + b)(a − b) = a² − b² to find 27 × 13.
  39. 39.Find the value of x² + 2xy + y² when x = 5 and y = 2.
  40. 40.Use (a + b)² = a² + 2ab + b² to find 66².

Answer key

  1. 5476
  2. 5
  3. 7171
  4. 52
  5. 1425
  6. 85
  7. 109
  8. 9975
  9. 1519
  10. 25
  11. 1849
  12. 4225
  13. 741
  14. 1479
  15. 3364
  16. 1849
  17. 5184
  18. 16
  19. 2809
  20. 1444
  21. 1591
  22. 1591
  23. 435
  24. 819
  25. 26
  26. 5376
  27. 1296
  28. 2499
  29. 4200
  30. 377
  31. 13
  32. 122
  33. 4
  34. 225
  35. 676
  36. 17
  37. 2436
  38. 351
  39. 49
  40. 4356

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