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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 1 · 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.If a + b = 5 and ab = 4, what is a² + b²?
  2. 2.Find the value of x² + 2xy + y² when x = 6 and y = 5.
  3. 3.Use a² − b² = (a + b)(a − b) to find 93² − 63².
  4. 4.Use (a + b)² = a² + 2ab + b² to find 52².
  5. 5.Use (a − b)² = a² − 2ab + b² to find 24².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 41².
  7. 7.If a + b = 10 and ab = 21, what is a² + b²?
  8. 8.Find the value of x² − y² when x = 12 and y = 9.
  9. 9.Use (a − b)² = a² − 2ab + b² to find 57².
  10. 10.If a + b = 3 and ab = 2, what is a² + b²?
  11. 11.Use (a + b)² = a² + 2ab + b² to find 63².
  12. 12.Use a² − b² = (a + b)(a − b) to find 45² − 35².
  13. 13.Use a² − b² = (a + b)(a − b) to find 82² − 53².
  14. 14.If a + b = 15 and ab = 44, what is a² + b²?
  15. 15.Use (a − b)² = a² − 2ab + b² to find 83².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 27².
  17. 17.If a + b = 14 and ab = 33, what is a² + b²?
  18. 18.Use (a + b)(a − b) = a² − b² to find 73 × 67.
  19. 19.Use a² − b² = (a + b)(a − b) to find 28² − 5².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 73².
  21. 21.Use (a + b)(a − b) = a² − b² to find 36 × 24.
  22. 22.Use (a + b)(a − b) = a² − b² to find 22 × 18.
  23. 23.Use (a + b)² = a² + 2ab + b² to find 34².
  24. 24.Use a² − b² = (a + b)(a − b) to find 41² − 16².
  25. 25.Use (a − b)² = a² − 2ab + b² to find 62².
  26. 26.Find the value of x² − y² when x = 6 and y = 5.
  27. 27.Use (a + b)² = a² + 2ab + b² to find 49².
  28. 28.If a + b = 13 and ab = 12, what is a² + b²?
  29. 29.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  30. 30.Use (a − b)² = a² − 2ab + b² to find 78².
  31. 31.Use (a + b)(a − b) = a² − b² to find 39 × 21.
  32. 32.Use a² − b² = (a + b)(a − b) to find 51² − 46².
  33. 33.Use (a + b)(a − b) = a² − b² to find 27 × 13.
  34. 34.Use (a + b)² = a² + 2ab + b² to find 43².
  35. 35.Use a² − b² = (a + b)(a − b) to find 31² − 18².
  36. 36.Use (a + b)² = a² + 2ab + b² to find 67².
  37. 37.Use a² − b² = (a + b)(a − b) to find 25² − 21².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 13².
  39. 39.Use (a + b)(a − b) = a² − b² to find 94 × 86.
  40. 40.Use (a + b)² = a² + 2ab + b² to find 82².

Answer key

  1. 17
  2. 121
  3. 4680
  4. 2704
  5. 576
  6. 1681
  7. 58
  8. 63
  9. 3249
  10. 5
  11. 3969
  12. 800
  13. 3915
  14. 137
  15. 6889
  16. 729
  17. 130
  18. 4891
  19. 759
  20. 5329
  21. 864
  22. 396
  23. 1156
  24. 1425
  25. 3844
  26. 11
  27. 2401
  28. 145
  29. 899
  30. 6084
  31. 819
  32. 485
  33. 351
  34. 1849
  35. 637
  36. 4489
  37. 184
  38. 169
  39. 8084
  40. 6724

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