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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 565 · 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 43².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 49².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 26².
  4. 4.If a − b = 1 and ab = 2, what is a² + b²?
  5. 5.Use a² − b² = (a + b)(a − b) to find 72² − 33².
  6. 6.Find the value of x² − y² when x = 12 and y = 2.
  7. 7.Find the value of x² − 2xy + y² when x = 14 and y = 11.
  8. 8.Use a² − b² = (a + b)(a − b) to find 25² − 2².
  9. 9.Use a² − b² = (a + b)(a − b) to find 24² − 16².
  10. 10.Use (a + b)(a − b) = a² − b² to find 73 × 67.
  11. 11.Use (a + b)(a − b) = a² − b² to find 56 × 44.
  12. 12.Use a² − b² = (a + b)(a − b) to find 27² − 13².
  13. 13.Use (a + b)(a − b) = a² − b² to find 98 × 82.
  14. 14.Use (a + b)(a − b) = a² − b² to find 25 × 15.
  15. 15.If a + b = 5 and ab = 6, what is a² + b²?
  16. 16.Use (a − b)² = a² − 2ab + b² to find 75².
  17. 17.If a − b = 6 and ab = 40, what is a² + b²?
  18. 18.Use a² − b² = (a + b)(a − b) to find 55² − 35².
  19. 19.Find the value of x² − y² when x = 9 and y = 1.
  20. 20.Use a² − b² = (a + b)(a − b) to find 25² − 10².
  21. 21.Find the value of x² + 2xy + y² when x = 6 and y = 5.
  22. 22.Use (a + b)(a − b) = a² − b² to find 103 × 97.
  23. 23.Use (a + b)² = a² + 2ab + b² to find 41².
  24. 24.Find the value of x² + 2xy + y² when x = 4 and y = 2.
  25. 25.If a + b = 5 and ab = 4, what is a² + b²?
  26. 26.Use (a + b)² = a² + 2ab + b² to find 14².
  27. 27.Use a² − b² = (a + b)(a − b) to find 21² − 6².
  28. 28.Use (a − b)² = a² − 2ab + b² to find 25².
  29. 29.Use (a − b)² = a² − 2ab + b² to find 39².
  30. 30.Use (a − b)² = a² − 2ab + b² to find 44².
  31. 31.Use a² − b² = (a + b)(a − b) to find 81² − 21².
  32. 32.Use (a + b)² = a² + 2ab + b² to find 97².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 56².
  34. 34.Find the value of x² − y² when x = 3 and y = 1.
  35. 35.Use a² − b² = (a + b)(a − b) to find 60² − 58².
  36. 36.Use (a + b)(a − b) = a² − b² to find 22 × 18.
  37. 37.Use (a + b)² = a² + 2ab + b² to find 42².
  38. 38.Use a² − b² = (a + b)(a − b) to find 52² − 5².
  39. 39.Find the value of x² − 2xy + y² when x = 5 and y = 4.
  40. 40.If a − b = 4 and ab = 12, what is a² + b²?

Answer key

  1. 1849
  2. 2401
  3. 676
  4. 5
  5. 4095
  6. 140
  7. 9
  8. 621
  9. 320
  10. 4891
  11. 2464
  12. 560
  13. 8036
  14. 375
  15. 13
  16. 5625
  17. 116
  18. 1800
  19. 80
  20. 525
  21. 121
  22. 9991
  23. 1681
  24. 36
  25. 17
  26. 196
  27. 405
  28. 625
  29. 1521
  30. 1936
  31. 6120
  32. 9409
  33. 3136
  34. 8
  35. 236
  36. 396
  37. 1764
  38. 2679
  39. 1
  40. 40

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