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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 519 · 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 26².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 55².
  3. 3.Use a² − b² = (a + b)(a − b) to find 76² − 17².
  4. 4.Use a² − b² = (a + b)(a − b) to find 28² − 15².
  5. 5.Use (a − b)² = a² − 2ab + b² to find 24².
  6. 6.Use a² − b² = (a + b)(a − b) to find 39² − 38².
  7. 7.Use a² − b² = (a + b)(a − b) to find 77² − 64².
  8. 8.If a − b = 2 and ab = 48, what is a² + b²?
  9. 9.Use (a − b)² = a² − 2ab + b² to find 63².
  10. 10.Find the value of x² − y² when x = 4 and y = 1.
  11. 11.Find the value of x² + 2xy + y² when x = 9 and y = 5.
  12. 12.Use a² − b² = (a + b)(a − b) to find 46² − 11².
  13. 13.If a + b = 7 and ab = 6, what is a² + b²?
  14. 14.Find the value of x² − y² when x = 10 and y = 8.
  15. 15.Use a² − b² = (a + b)(a − b) to find 46² − 39².
  16. 16.If a + b = 7 and ab = 12, what is a² + b²?
  17. 17.Use a² − b² = (a + b)(a − b) to find 25² − 5².
  18. 18.Use (a + b)² = a² + 2ab + b² to find 93².
  19. 19.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  20. 20.Use a² − b² = (a + b)(a − b) to find 92² − 65².
  21. 21.Use (a − b)² = a² − 2ab + b² to find 68².
  22. 22.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  23. 23.Use (a + b)(a − b) = a² − b² to find 97 × 83.
  24. 24.Find the value of x² − y² when x = 11 and y = 2.
  25. 25.If a − b = 2 and ab = 24, what is a² + b²?
  26. 26.Use (a − b)² = a² − 2ab + b² to find 96².
  27. 27.If a + b = 9 and ab = 18, what is a² + b²?
  28. 28.If a + b = 14 and ab = 45, what is a² + b²?
  29. 29.Find the value of x² − y² when x = 12 and y = 9.
  30. 30.Use a² − b² = (a + b)(a − b) to find 33² − 23².
  31. 31.Use (a + b)² = a² + 2ab + b² to find 101².
  32. 32.Use (a + b)² = a² + 2ab + b² to find 97².
  33. 33.Use (a + b)(a − b) = a² − b² to find 23 × 17.
  34. 34.Use (a + b)(a − b) = a² − b² to find 92 × 88.
  35. 35.Use (a + b)² = a² + 2ab + b² to find 84².
  36. 36.Find the value of x² − y² when x = 13 and y = 12.
  37. 37.Use (a + b)(a − b) = a² − b² to find 33 × 27.
  38. 38.If a + b = 20 and ab = 96, what is a² + b²?
  39. 39.Use a² − b² = (a + b)(a − b) to find 48² − 3².
  40. 40.Use (a + b)² = a² + 2ab + b² to find 109².

Answer key

  1. 676
  2. 3025
  3. 5487
  4. 559
  5. 576
  6. 77
  7. 1833
  8. 100
  9. 3969
  10. 15
  11. 196
  12. 1995
  13. 37
  14. 36
  15. 595
  16. 25
  17. 600
  18. 8649
  19. 25
  20. 4239
  21. 4624
  22. 875
  23. 8051
  24. 117
  25. 52
  26. 9216
  27. 45
  28. 106
  29. 63
  30. 560
  31. 10201
  32. 9409
  33. 391
  34. 8096
  35. 7056
  36. 25
  37. 891
  38. 208
  39. 2295
  40. 11881

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