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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 473 · 40 sums
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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)(a − b) = a² − b² to find 33 × 27.
  2. 2.Use (a + b)² = a² + 2ab + b² to find 37².
  3. 3.Use (a + b)² = a² + 2ab + b² to find 24².
  4. 4.Use (a + b)(a − b) = a² − b² to find 24 × 16.
  5. 5.Use (a + b)(a − b) = a² − b² to find 27 × 13.
  6. 6.Find the value of x² − 2xy + y² when x = 6 and y = 5.
  7. 7.Use (a − b)² = a² − 2ab + b² to find 19².
  8. 8.Use (a + b)(a − b) = a² − b² to find 87 × 73.
  9. 9.Use (a − b)² = a² − 2ab + b² to find 63².
  10. 10.Use (a + b)(a − b) = a² − b² to find 102 × 98.
  11. 11.Use a² − b² = (a + b)(a − b) to find 94² − 59².
  12. 12.Use (a + b)(a − b) = a² − b² to find 92 × 88.
  13. 13.Use (a + b)(a − b) = a² − b² to find 71 × 69.
  14. 14.Use (a + b)² = a² + 2ab + b² to find 29².
  15. 15.If a + b = 17 and ab = 70, what is a² + b²?
  16. 16.Use (a + b)(a − b) = a² − b² to find 36 × 24.
  17. 17.Use a² − b² = (a + b)(a − b) to find 62² − 1².
  18. 18.If a + b = 3 and ab = 2, what is a² + b²?
  19. 19.Use (a − b)² = a² − 2ab + b² to find 89².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 15².
  21. 21.Use (a + b)² = a² + 2ab + b² to find 13².
  22. 22.Use (a + b)² = a² + 2ab + b² to find 56².
  23. 23.Use (a − b)² = a² − 2ab + b² to find 28².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 91².
  25. 25.Use (a + b)(a − b) = a² − b² to find 56 × 44.
  26. 26.Use (a + b)(a − b) = a² − b² to find 91 × 89.
  27. 27.Use (a + b)² = a² + 2ab + b² to find 49².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 22².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 33².
  30. 30.Find the value of x² − 2xy + y² when x = 4 and y = 2.
  31. 31.Use (a + b)(a − b) = a² − b² to find 26 × 14.
  32. 32.If a + b = 10 and ab = 24, what is a² + b²?
  33. 33.Use a² − b² = (a + b)(a − b) to find 86² − 54².
  34. 34.Use (a − b)² = a² − 2ab + b² to find 54².
  35. 35.Use (a + b)² = a² + 2ab + b² to find 108².
  36. 36.Use a² − b² = (a + b)(a − b) to find 20² − 1².
  37. 37.If a − b = 4 and ab = 21, what is a² + b²?
  38. 38.Use (a + b)² = a² + 2ab + b² to find 17².
  39. 39.Use (a + b)(a − b) = a² − b² to find 108 × 92.
  40. 40.Use a² − b² = (a + b)(a − b) to find 41² − 14².

Answer key

  1. 891
  2. 1369
  3. 576
  4. 384
  5. 351
  6. 1
  7. 361
  8. 6351
  9. 3969
  10. 9996
  11. 5355
  12. 8096
  13. 4899
  14. 841
  15. 149
  16. 864
  17. 3843
  18. 5
  19. 7921
  20. 225
  21. 169
  22. 3136
  23. 784
  24. 8281
  25. 2464
  26. 8099
  27. 2401
  28. 484
  29. 1089
  30. 4
  31. 364
  32. 52
  33. 4480
  34. 2916
  35. 11664
  36. 399
  37. 58
  38. 289
  39. 9936
  40. 1485

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