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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 754 · 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 87².
  2. 2.Use (a − b)² = a² − 2ab + b² to find 71².
  3. 3.Find the value of x² − y² when x = 14 and y = 11.
  4. 4.Find the value of x² − 2xy + y² when x = 6 and y = 1.
  5. 5.Use (a + b)² = a² + 2ab + b² to find 103².
  6. 6.Use (a + b)² = a² + 2ab + b² to find 53².
  7. 7.Use (a + b)(a − b) = a² − b² to find 82 × 78.
  8. 8.Use (a + b)(a − b) = a² − b² to find 66 × 54.
  9. 9.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  10. 10.Use a² − b² = (a + b)(a − b) to find 31² − 23².
  11. 11.Use (a + b)(a − b) = a² − b² to find 57 × 43.
  12. 12.Use a² − b² = (a + b)(a − b) to find 42² − 30².
  13. 13.If a + b = 10 and ab = 16, what is a² + b²?
  14. 14.Use (a − b)² = a² − 2ab + b² to find 83².
  15. 15.Use (a + b)(a − b) = a² − b² to find 51 × 49.
  16. 16.Find the value of x² + 2xy + y² when x = 8 and y = 4.
  17. 17.Find the value of x² − 2xy + y² when x = 6 and y = 4.
  18. 18.Use a² − b² = (a + b)(a − b) to find 35² − 34².
  19. 19.Use a² − b² = (a + b)(a − b) to find 80² − 25².
  20. 20.Use a² − b² = (a + b)(a − b) to find 74² − 22².
  21. 21.Find the value of x² − 2xy + y² when x = 3 and y = 2.
  22. 22.Use a² − b² = (a + b)(a − b) to find 24² − 3².
  23. 23.Use (a + b)(a − b) = a² − b² to find 101 × 99.
  24. 24.Find the value of x² + 2xy + y² when x = 4 and y = 3.
  25. 25.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  26. 26.Use (a + b)(a − b) = a² − b² to find 41 × 39.
  27. 27.Use (a + b)(a − b) = a² − b² to find 28 × 12.
  28. 28.Use (a + b)² = a² + 2ab + b² to find 41².
  29. 29.Find the value of x² − y² when x = 9 and y = 7.
  30. 30.Use a² − b² = (a + b)(a − b) to find 40² − 23².
  31. 31.Use (a + b)² = a² + 2ab + b² to find 64².
  32. 32.Use (a − b)² = a² − 2ab + b² to find 19².
  33. 33.Use (a + b)(a − b) = a² − b² to find 65 × 55.
  34. 34.Use (a − b)² = a² − 2ab + b² to find 95².
  35. 35.Use a² − b² = (a + b)(a − b) to find 87² − 72².
  36. 36.If a + b = 11 and ab = 24, what is a² + b²?
  37. 37.Use (a + b)(a − b) = a² − b² to find 45 × 35.
  38. 38.Use (a + b)(a − b) = a² − b² to find 85 × 75.
  39. 39.If a − b = 8 and ab = 33, what is a² + b²?
  40. 40.Find the value of x² − 2xy + y² when x = 4 and y = 1.

Answer key

  1. 7569
  2. 5041
  3. 75
  4. 25
  5. 10609
  6. 2809
  7. 6396
  8. 3564
  9. 875
  10. 432
  11. 2451
  12. 864
  13. 68
  14. 6889
  15. 2499
  16. 144
  17. 4
  18. 69
  19. 5775
  20. 4992
  21. 1
  22. 567
  23. 9999
  24. 49
  25. 899
  26. 1599
  27. 336
  28. 1681
  29. 32
  30. 1071
  31. 4096
  32. 361
  33. 3575
  34. 9025
  35. 2385
  36. 73
  37. 1575
  38. 6375
  39. 130
  40. 9

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