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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 522 · 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 − y² when x = 12 and y = 8.
  2. 2.If a + b = 7 and ab = 12, what is a² + b²?
  3. 3.Use (a − b)² = a² − 2ab + b² to find 83².
  4. 4.Use (a + b)² = a² + 2ab + b² to find 33².
  5. 5.Find the value of x² − 2xy + y² when x = 8 and y = 1.
  6. 6.If a + b = 13 and ab = 22, what is a² + b²?
  7. 7.Use (a + b)² = a² + 2ab + b² to find 32².
  8. 8.Use (a − b)² = a² − 2ab + b² to find 21².
  9. 9.Use (a − b)² = a² − 2ab + b² to find 14².
  10. 10.Use (a − b)² = a² − 2ab + b² to find 16².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 98².
  12. 12.Use (a + b)(a − b) = a² − b² to find 51 × 49.
  13. 13.Use (a − b)² = a² − 2ab + b² to find 55².
  14. 14.Find the value of x² − 2xy + y² when x = 10 and y = 6.
  15. 15.Use (a + b)(a − b) = a² − b² to find 91 × 89.
  16. 16.Use (a + b)² = a² + 2ab + b² to find 107².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 59².
  18. 18.Use a² − b² = (a + b)(a − b) to find 62² − 22².
  19. 19.Use (a + b)(a − b) = a² − b² to find 54 × 46.
  20. 20.Use a² − b² = (a + b)(a − b) to find 64² − 34².
  21. 21.Use a² − b² = (a + b)(a − b) to find 70² − 26².
  22. 22.Use (a + b)² = a² + 2ab + b² to find 95².
  23. 23.Use a² − b² = (a + b)(a − b) to find 55² − 39².
  24. 24.Use a² − b² = (a + b)(a − b) to find 89² − 71².
  25. 25.Use (a + b)(a − b) = a² − b² to find 41 × 39.
  26. 26.Use (a − b)² = a² − 2ab + b² to find 45².
  27. 27.Use (a + b)² = a² + 2ab + b² to find 13².
  28. 28.Find the value of x² + 2xy + y² when x = 14 and y = 13.
  29. 29.If a − b = 1 and ab = 30, what is a² + b²?
  30. 30.If a + b = 12 and ab = 27, what is a² + b²?
  31. 31.Find the value of x² + 2xy + y² when x = 6 and y = 3.
  32. 32.If a + b = 19 and ab = 84, what is a² + b²?
  33. 33.If a + b = 6 and ab = 5, what is a² + b²?
  34. 34.Use (a + b)² = a² + 2ab + b² to find 34².
  35. 35.Use (a − b)² = a² − 2ab + b² to find 86².
  36. 36.If a + b = 15 and ab = 54, what is a² + b²?
  37. 37.Use (a − b)² = a² − 2ab + b² to find 49².
  38. 38.Use (a + b)² = a² + 2ab + b² to find 25².
  39. 39.Use a² − b² = (a + b)(a − b) to find 77² − 29².
  40. 40.Use a² − b² = (a + b)(a − b) to find 65² − 47².

Answer key

  1. 80
  2. 25
  3. 6889
  4. 1089
  5. 49
  6. 125
  7. 1024
  8. 441
  9. 196
  10. 256
  11. 9604
  12. 2499
  13. 3025
  14. 16
  15. 8099
  16. 11449
  17. 3481
  18. 3360
  19. 2484
  20. 2940
  21. 4224
  22. 9025
  23. 1504
  24. 2880
  25. 1599
  26. 2025
  27. 169
  28. 729
  29. 61
  30. 90
  31. 81
  32. 193
  33. 26
  34. 1156
  35. 7396
  36. 117
  37. 2401
  38. 625
  39. 5088
  40. 2016

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