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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 770 · 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 33².
  2. 2.If a + b = 23 and ab = 132, what is a² + b²?
  3. 3.Use (a + b)² = a² + 2ab + b² to find 107².
  4. 4.Use a² − b² = (a + b)(a − b) to find 74² − 11².
  5. 5.Use (a − b)² = a² − 2ab + b² to find 42².
  6. 6.Use (a + b)(a − b) = a² − b² to find 88 × 72.
  7. 7.Use (a + b)(a − b) = a² − b² to find 71 × 69.
  8. 8.Find the value of x² + 2xy + y² when x = 6 and y = 4.
  9. 9.Use (a + b)(a − b) = a² − b² to find 51 × 49.
  10. 10.Use a² − b² = (a + b)(a − b) to find 26² − 21².
  11. 11.Use (a + b)² = a² + 2ab + b² to find 53².
  12. 12.If a + b = 10 and ab = 21, what is a² + b²?
  13. 13.Use (a + b)² = a² + 2ab + b² to find 27².
  14. 14.Use (a − b)² = a² − 2ab + b² to find 37².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 55².
  16. 16.Find the value of x² + 2xy + y² when x = 7 and y = 5.
  17. 17.Use (a − b)² = a² − 2ab + b² to find 21².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 58².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 57².
  20. 20.Use (a + b)² = a² + 2ab + b² to find 26².
  21. 21.Use (a + b)² = a² + 2ab + b² to find 38².
  22. 22.If a + b = 10 and ab = 24, what is a² + b²?
  23. 23.Use (a − b)² = a² − 2ab + b² to find 74².
  24. 24.Use (a + b)(a − b) = a² − b² to find 96 × 84.
  25. 25.If a − b = 2 and ab = 15, what is a² + b²?
  26. 26.Use (a + b)² = a² + 2ab + b² to find 44².
  27. 27.Find the value of x² + 2xy + y² when x = 7 and y = 6.
  28. 28.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  29. 29.Use (a + b)(a − b) = a² − b² to find 97 × 83.
  30. 30.Use (a − b)² = a² − 2ab + b² to find 86².
  31. 31.Use (a + b)(a − b) = a² − b² to find 24 × 16.
  32. 32.Use (a − b)² = a² − 2ab + b² to find 22².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 15².
  34. 34.If a + b = 8 and ab = 15, what is a² + b²?
  35. 35.Use (a + b)(a − b) = a² − b² to find 67 × 53.
  36. 36.Use a² − b² = (a + b)(a − b) to find 83² − 58².
  37. 37.Find the value of x² − y² when x = 12 and y = 5.
  38. 38.Use (a + b)(a − b) = a² − b² to find 44 × 36.
  39. 39.If a − b = 4 and ab = 12, what is a² + b²?
  40. 40.Use (a − b)² = a² − 2ab + b² to find 38².

Answer key

  1. 1089
  2. 265
  3. 11449
  4. 5355
  5. 1764
  6. 6336
  7. 4899
  8. 100
  9. 2499
  10. 235
  11. 2809
  12. 58
  13. 729
  14. 1369
  15. 3025
  16. 144
  17. 441
  18. 3364
  19. 3249
  20. 676
  21. 1444
  22. 52
  23. 5476
  24. 8064
  25. 34
  26. 1936
  27. 169
  28. 1591
  29. 8051
  30. 7396
  31. 384
  32. 484
  33. 225
  34. 34
  35. 3551
  36. 3525
  37. 119
  38. 1584
  39. 40
  40. 1444

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