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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 726 · 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 94².
  2. 2.Use a² − b² = (a + b)(a − b) to find 50² − 40².
  3. 3.Find the value of x² + 2xy + y² when x = 7 and y = 1.
  4. 4.Find the value of x² − y² when x = 8 and y = 3.
  5. 5.Use (a − b)² = a² − 2ab + b² to find 29².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 71².
  7. 7.Use (a − b)² = a² − 2ab + b² to find 32².
  8. 8.Use (a − b)² = a² − 2ab + b² to find 53².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 22².
  10. 10.Use a² − b² = (a + b)(a − b) to find 39² − 23².
  11. 11.Use (a + b)(a − b) = a² − b² to find 63 × 57.
  12. 12.Use (a − b)² = a² − 2ab + b² to find 34².
  13. 13.If a + b = 16 and ab = 63, what is a² + b²?
  14. 14.Use (a + b)(a − b) = a² − b² to find 104 × 96.
  15. 15.Find the value of x² − 2xy + y² when x = 4 and y = 2.
  16. 16.Use (a − b)² = a² − 2ab + b² to find 31².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 36².
  18. 18.Use (a + b)(a − b) = a² − b² to find 99 × 81.
  19. 19.Use (a + b)² = a² + 2ab + b² to find 17².
  20. 20.Find the value of x² − 2xy + y² when x = 6 and y = 1.
  21. 21.Find the value of x² − y² when x = 11 and y = 10.
  22. 22.Use a² − b² = (a + b)(a − b) to find 31² − 14².
  23. 23.Use (a − b)² = a² − 2ab + b² to find 26².
  24. 24.If a − b = 7 and ab = 8, what is a² + b²?
  25. 25.Use (a − b)² = a² − 2ab + b² to find 18².
  26. 26.If a − b = 5 and ab = 24, what is a² + b²?
  27. 27.Use (a − b)² = a² − 2ab + b² to find 74².
  28. 28.If a + b = 3 and ab = 2, what is a² + b²?
  29. 29.Use (a + b)(a − b) = a² − b² to find 81 × 79.
  30. 30.Use (a + b)(a − b) = a² − b² to find 22 × 18.
  31. 31.If a − b = 3 and ab = 70, what is a² + b²?
  32. 32.Use a² − b² = (a + b)(a − b) to find 91² − 27².
  33. 33.Use (a − b)² = a² − 2ab + b² to find 82².
  34. 34.Use (a + b)(a − b) = a² − b² to find 76 × 64.
  35. 35.Use a² − b² = (a + b)(a − b) to find 28² − 20².
  36. 36.Use (a − b)² = a² − 2ab + b² to find 24².
  37. 37.Use (a + b)(a − b) = a² − b² to find 57 × 43.
  38. 38.Use (a + b)² = a² + 2ab + b² to find 61².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 13².
  40. 40.If a − b = 2 and ab = 24, what is a² + b²?

Answer key

  1. 8836
  2. 900
  3. 64
  4. 55
  5. 841
  6. 5041
  7. 1024
  8. 2809
  9. 484
  10. 992
  11. 3591
  12. 1156
  13. 130
  14. 9984
  15. 4
  16. 961
  17. 1296
  18. 8019
  19. 289
  20. 25
  21. 21
  22. 765
  23. 676
  24. 65
  25. 324
  26. 73
  27. 5476
  28. 5
  29. 6399
  30. 396
  31. 149
  32. 7552
  33. 6724
  34. 4864
  35. 384
  36. 576
  37. 2451
  38. 3721
  39. 169
  40. 52

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