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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 935 · 40 sums
TalentJR

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 27².
  2. 2.If a − b = 3 and ab = 4, what is a² + b²?
  3. 3.Find the value of x² − y² when x = 14 and y = 11.
  4. 4.Use (a − b)² = a² − 2ab + b² to find 17².
  5. 5.Find the value of x² − y² when x = 7 and y = 6.
  6. 6.Use (a − b)² = a² − 2ab + b² to find 37².
  7. 7.Use (a + b)(a − b) = a² − b² to find 22 × 18.
  8. 8.Use (a + b)(a − b) = a² − b² to find 23 × 17.
  9. 9.Find the value of x² − y² when x = 13 and y = 9.
  10. 10.Use (a − b)² = a² − 2ab + b² to find 73².
  11. 11.Use (a + b)(a − b) = a² − b² to find 72 × 68.
  12. 12.If a − b = 9 and ab = 22, what is a² + b²?
  13. 13.Use (a − b)² = a² − 2ab + b² to find 12².
  14. 14.Use a² − b² = (a + b)(a − b) to find 87² − 28².
  15. 15.If a + b = 13 and ab = 42, what is a² + b²?
  16. 16.Use (a − b)² = a² − 2ab + b² to find 59².
  17. 17.Use a² − b² = (a + b)(a − b) to find 42² − 33².
  18. 18.Use a² − b² = (a + b)(a − b) to find 62² − 29².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 37².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 23².
  21. 21.Use a² − b² = (a + b)(a − b) to find 84² − 83².
  22. 22.Use a² − b² = (a + b)(a − b) to find 95² − 70².
  23. 23.Use a² − b² = (a + b)(a − b) to find 69² − 42².
  24. 24.Use (a + b)(a − b) = a² − b² to find 36 × 24.
  25. 25.Use (a + b)² = a² + 2ab + b² to find 32².
  26. 26.Use (a − b)² = a² − 2ab + b² to find 55².
  27. 27.If a + b = 17 and ab = 72, what is a² + b²?
  28. 28.Find the value of x² + 2xy + y² when x = 6 and y = 1.
  29. 29.If a + b = 10 and ab = 21, what is a² + b²?
  30. 30.If a + b = 21 and ab = 108, what is a² + b²?
  31. 31.Use (a − b)² = a² − 2ab + b² to find 45².
  32. 32.Use (a + b)(a − b) = a² − b² to find 47 × 33.
  33. 33.Use a² − b² = (a + b)(a − b) to find 63² − 29².
  34. 34.Use a² − b² = (a + b)(a − b) to find 89² − 1².
  35. 35.Use a² − b² = (a + b)(a − b) to find 69² − 26².
  36. 36.Find the value of x² − 2xy + y² when x = 11 and y = 6.
  37. 37.Use a² − b² = (a + b)(a − b) to find 27² − 2².
  38. 38.If a − b = 3 and ab = 10, what is a² + b²?
  39. 39.Find the value of x² + 2xy + y² when x = 11 and y = 2.
  40. 40.Use (a − b)² = a² − 2ab + b² to find 22².

Answer key

  1. 729
  2. 17
  3. 75
  4. 289
  5. 13
  6. 1369
  7. 396
  8. 391
  9. 88
  10. 5329
  11. 4896
  12. 125
  13. 144
  14. 6785
  15. 85
  16. 3481
  17. 675
  18. 3003
  19. 1369
  20. 529
  21. 167
  22. 4125
  23. 2997
  24. 864
  25. 1024
  26. 3025
  27. 145
  28. 49
  29. 58
  30. 225
  31. 2025
  32. 1551
  33. 3128
  34. 7920
  35. 4085
  36. 25
  37. 725
  38. 29
  39. 169
  40. 484

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