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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 771 · 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)² = a² + 2ab + b² to find 46².
  2. 2.Use (a − b)² = a² − 2ab + b² to find 23².
  3. 3.Find the value of x² − y² when x = 9 and y = 1.
  4. 4.If a + b = 3 and ab = 2, what is a² + b²?
  5. 5.Use (a + b)² = a² + 2ab + b² to find 62².
  6. 6.Use (a + b)(a − b) = a² − b² to find 32 × 28.
  7. 7.Use a² − b² = (a + b)(a − b) to find 68² − 53².
  8. 8.Use (a − b)² = a² − 2ab + b² to find 35².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 61².
  10. 10.If a − b = 4 and ab = 5, what is a² + b²?
  11. 11.Use (a + b)² = a² + 2ab + b² to find 29².
  12. 12.Use (a + b)² = a² + 2ab + b² to find 11².
  13. 13.Find the value of x² + 2xy + y² when x = 9 and y = 8.
  14. 14.Use (a − b)² = a² − 2ab + b² to find 95².
  15. 15.Find the value of x² + 2xy + y² when x = 5 and y = 4.
  16. 16.Use (a + b)(a − b) = a² − b² to find 25 × 15.
  17. 17.Use (a + b)(a − b) = a² − b² to find 98 × 82.
  18. 18.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  19. 19.Find the value of x² − y² when x = 3 and y = 1.
  20. 20.Use (a + b)(a − b) = a² − b² to find 68 × 52.
  21. 21.Use (a − b)² = a² − 2ab + b² to find 92².
  22. 22.Use (a − b)² = a² − 2ab + b² to find 54².
  23. 23.If a − b = 2 and ab = 48, what is a² + b²?
  24. 24.Use a² − b² = (a + b)(a − b) to find 33² − 29².
  25. 25.Use (a + b)(a − b) = a² − b² to find 86 × 74.
  26. 26.Find the value of x² + 2xy + y² when x = 3 and y = 1.
  27. 27.If a − b = 6 and ab = 55, what is a² + b²?
  28. 28.If a + b = 14 and ab = 48, what is a² + b²?
  29. 29.Use (a + b)² = a² + 2ab + b² to find 64².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 77².
  31. 31.Use (a + b)² = a² + 2ab + b² to find 87².
  32. 32.Use (a + b)² = a² + 2ab + b² to find 34².
  33. 33.Find the value of x² − y² when x = 15 and y = 5.
  34. 34.Use a² − b² = (a + b)(a − b) to find 30² − 3².
  35. 35.Use (a + b)(a − b) = a² − b² to find 71 × 69.
  36. 36.Find the value of x² − y² when x = 7 and y = 4.
  37. 37.Use (a + b)(a − b) = a² − b² to find 59 × 41.
  38. 38.Use a² − b² = (a + b)(a − b) to find 51² − 19².
  39. 39.Find the value of x² + 2xy + y² when x = 13 and y = 4.
  40. 40.Use a² − b² = (a + b)(a − b) to find 65² − 21².

Answer key

  1. 2116
  2. 529
  3. 80
  4. 5
  5. 3844
  6. 896
  7. 1815
  8. 1225
  9. 3721
  10. 26
  11. 841
  12. 121
  13. 289
  14. 9025
  15. 81
  16. 375
  17. 8036
  18. 1591
  19. 8
  20. 3536
  21. 8464
  22. 2916
  23. 100
  24. 248
  25. 6364
  26. 16
  27. 146
  28. 100
  29. 4096
  30. 5929
  31. 7569
  32. 1156
  33. 200
  34. 891
  35. 4899
  36. 33
  37. 2419
  38. 2240
  39. 289
  40. 3784

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