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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 360 · 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 36².
  2. 2.Find the value of x² − 2xy + y² when x = 5 and y = 1.
  3. 3.Find the value of x² − 2xy + y² when x = 6 and y = 1.
  4. 4.Use (a − b)² = a² − 2ab + b² to find 21².
  5. 5.Use (a + b)² = a² + 2ab + b² to find 91².
  6. 6.Use (a + b)² = a² + 2ab + b² to find 66².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 58².
  8. 8.Use a² − b² = (a + b)(a − b) to find 66² − 43².
  9. 9.Use a² − b² = (a + b)(a − b) to find 81² − 1².
  10. 10.Use a² − b² = (a + b)(a − b) to find 26² − 3².
  11. 11.If a + b = 3 and ab = 2, what is a² + b²?
  12. 12.If a + b = 4 and ab = 3, what is a² + b²?
  13. 13.Use a² − b² = (a + b)(a − b) to find 93² − 86².
  14. 14.Use (a − b)² = a² − 2ab + b² to find 97².
  15. 15.Use a² − b² = (a + b)(a − b) to find 27² − 9².
  16. 16.Use (a + b)(a − b) = a² − b² to find 56 × 44.
  17. 17.Find the value of x² − 2xy + y² when x = 8 and y = 6.
  18. 18.Use (a − b)² = a² − 2ab + b² to find 15².
  19. 19.Use (a − b)² = a² − 2ab + b² to find 22².
  20. 20.Use a² − b² = (a + b)(a − b) to find 97² − 58².
  21. 21.Use (a − b)² = a² − 2ab + b² to find 58².
  22. 22.Use (a + b)(a − b) = a² − b² to find 44 × 36.
  23. 23.Use a² − b² = (a + b)(a − b) to find 55² − 22².
  24. 24.Find the value of x² − y² when x = 9 and y = 5.
  25. 25.Use a² − b² = (a + b)(a − b) to find 40² − 3².
  26. 26.Use a² − b² = (a + b)(a − b) to find 23² − 6².
  27. 27.Use (a + b)² = a² + 2ab + b² to find 107².
  28. 28.Use a² − b² = (a + b)(a − b) to find 95² − 13².
  29. 29.If a − b = 1 and ab = 2, what is a² + b²?
  30. 30.Use (a + b)² = a² + 2ab + b² to find 45².
  31. 31.Use (a + b)(a − b) = a² − b² to find 104 × 96.
  32. 32.Use a² − b² = (a + b)(a − b) to find 39² − 23².
  33. 33.Use a² − b² = (a + b)(a − b) to find 62² − 37².
  34. 34.Use a² − b² = (a + b)(a − b) to find 62² − 41².
  35. 35.Use (a − b)² = a² − 2ab + b² to find 35².
  36. 36.Use (a + b)² = a² + 2ab + b² to find 46².
  37. 37.Use (a + b)(a − b) = a² − b² to find 26 × 14.
  38. 38.Use (a + b)(a − b) = a² − b² to find 105 × 95.
  39. 39.Use (a + b)(a − b) = a² − b² to find 37 × 23.
  40. 40.If a − b = 6 and ab = 16, what is a² + b²?

Answer key

  1. 1296
  2. 16
  3. 25
  4. 441
  5. 8281
  6. 4356
  7. 3364
  8. 2507
  9. 6560
  10. 667
  11. 5
  12. 10
  13. 1253
  14. 9409
  15. 648
  16. 2464
  17. 4
  18. 225
  19. 484
  20. 6045
  21. 3364
  22. 1584
  23. 2541
  24. 56
  25. 1591
  26. 493
  27. 11449
  28. 8856
  29. 5
  30. 2025
  31. 9984
  32. 992
  33. 2475
  34. 2163
  35. 1225
  36. 2116
  37. 364
  38. 9975
  39. 851
  40. 68

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