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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 669 · 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.Find the value of x² + 2xy + y² when x = 8 and y = 2.
  2. 2.If a − b = 3 and ab = 10, what is a² + b²?
  3. 3.If a + b = 9 and ab = 14, what is a² + b²?
  4. 4.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  5. 5.Use (a + b)(a − b) = a² − b² to find 101 × 99.
  6. 6.If a + b = 10 and ab = 9, what is a² + b²?
  7. 7.Use (a − b)² = a² − 2ab + b² to find 94².
  8. 8.Use (a + b)² = a² + 2ab + b² to find 71².
  9. 9.Use (a + b)(a − b) = a² − b² to find 67 × 53.
  10. 10.Use (a − b)² = a² − 2ab + b² to find 71².
  11. 11.If a − b = 2 and ab = 3, what is a² + b²?
  12. 12.Use a² − b² = (a + b)(a − b) to find 61² − 35².
  13. 13.Use (a + b)² = a² + 2ab + b² to find 41².
  14. 14.Use (a + b)² = a² + 2ab + b² to find 99².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 68².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 37².
  17. 17.Find the value of x² + 2xy + y² when x = 12 and y = 11.
  18. 18.If a − b = 3 and ab = 88, what is a² + b²?
  19. 19.Find the value of x² − 2xy + y² when x = 15 and y = 10.
  20. 20.Use a² − b² = (a + b)(a − b) to find 88² − 18².
  21. 21.Use a² − b² = (a + b)(a − b) to find 59² − 14².
  22. 22.Use a² − b² = (a + b)(a − b) to find 87² − 12².
  23. 23.Use (a + b)(a − b) = a² − b² to find 64 × 56.
  24. 24.Use a² − b² = (a + b)(a − b) to find 90² − 48².
  25. 25.Use (a − b)² = a² − 2ab + b² to find 49².
  26. 26.If a + b = 12 and ab = 20, what is a² + b²?
  27. 27.Use (a + b)² = a² + 2ab + b² to find 13².
  28. 28.Find the value of x² − y² when x = 11 and y = 10.
  29. 29.Use (a + b)² = a² + 2ab + b² to find 86².
  30. 30.If a + b = 13 and ab = 12, what is a² + b²?
  31. 31.Use (a − b)² = a² − 2ab + b² to find 26².
  32. 32.Use a² − b² = (a + b)(a − b) to find 31² − 25².
  33. 33.Use a² − b² = (a + b)(a − b) to find 91² − 8².
  34. 34.Find the value of x² + 2xy + y² when x = 12 and y = 4.
  35. 35.Use (a − b)² = a² − 2ab + b² to find 43².
  36. 36.Use (a + b)(a − b) = a² − b² to find 61 × 59.
  37. 37.Use a² − b² = (a + b)(a − b) to find 27² − 18².
  38. 38.Use (a + b)(a − b) = a² − b² to find 93 × 87.
  39. 39.Use (a − b)² = a² − 2ab + b² to find 95².
  40. 40.Use (a + b)(a − b) = a² − b² to find 104 × 96.

Answer key

  1. 100
  2. 29
  3. 53
  4. 899
  5. 9999
  6. 82
  7. 8836
  8. 5041
  9. 3551
  10. 5041
  11. 10
  12. 2496
  13. 1681
  14. 9801
  15. 4624
  16. 1369
  17. 529
  18. 185
  19. 25
  20. 7420
  21. 3285
  22. 7425
  23. 3584
  24. 5796
  25. 2401
  26. 104
  27. 169
  28. 21
  29. 7396
  30. 145
  31. 676
  32. 336
  33. 8217
  34. 256
  35. 1849
  36. 3599
  37. 405
  38. 8091
  39. 9025
  40. 9984

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