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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 748 · 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 53².
  2. 2.Use a² − b² = (a + b)(a − b) to find 39² − 28².
  3. 3.Use (a + b)² = a² + 2ab + b² to find 52².
  4. 4.Find the value of x² − 2xy + y² when x = 11 and y = 9.
  5. 5.Use (a + b)(a − b) = a² − b² to find 105 × 95.
  6. 6.Use (a + b)² = a² + 2ab + b² to find 42².
  7. 7.Use (a + b)(a − b) = a² − b² to find 55 × 45.
  8. 8.Use (a + b)(a − b) = a² − b² to find 28 × 12.
  9. 9.Use (a + b)² = a² + 2ab + b² to find 107².
  10. 10.Find the value of x² + 2xy + y² when x = 8 and y = 2.
  11. 11.Use (a + b)(a − b) = a² − b² to find 24 × 16.
  12. 12.Use (a + b)² = a² + 2ab + b² to find 13².
  13. 13.If a − b = 7 and ab = 30, what is a² + b²?
  14. 14.Use (a − b)² = a² − 2ab + b² to find 52².
  15. 15.Use a² − b² = (a + b)(a − b) to find 81² − 31².
  16. 16.Find the value of x² + 2xy + y² when x = 15 and y = 12.
  17. 17.Use a² − b² = (a + b)(a − b) to find 81² − 46².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 34².
  19. 19.If a + b = 4 and ab = 3, what is a² + b²?
  20. 20.If a + b = 12 and ab = 11, what is a² + b²?
  21. 21.Find the value of x² − 2xy + y² when x = 13 and y = 8.
  22. 22.Use (a − b)² = a² − 2ab + b² to find 56².
  23. 23.Use (a + b)(a − b) = a² − b² to find 71 × 69.
  24. 24.If a + b = 20 and ab = 99, what is a² + b²?
  25. 25.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  26. 26.Find the value of x² − y² when x = 13 and y = 8.
  27. 27.Find the value of x² + 2xy + y² when x = 9 and y = 7.
  28. 28.Use (a + b)² = a² + 2ab + b² to find 75².
  29. 29.Use (a − b)² = a² − 2ab + b² to find 76².
  30. 30.Use (a − b)² = a² − 2ab + b² to find 68².
  31. 31.Use a² − b² = (a + b)(a − b) to find 50² − 26².
  32. 32.Use (a + b)² = a² + 2ab + b² to find 78².
  33. 33.Use (a + b)(a − b) = a² − b² to find 22 × 18.
  34. 34.If a + b = 6 and ab = 8, what is a² + b²?
  35. 35.Use a² − b² = (a + b)(a − b) to find 20² − 19².
  36. 36.Find the value of x² + 2xy + y² when x = 5 and y = 2.
  37. 37.Use a² − b² = (a + b)(a − b) to find 91² − 87².
  38. 38.Use (a + b)² = a² + 2ab + b² to find 73².
  39. 39.Use (a + b)(a − b) = a² − b² to find 61 × 59.
  40. 40.Find the value of x² − y² when x = 12 and y = 10.

Answer key

  1. 2809
  2. 737
  3. 2704
  4. 4
  5. 9975
  6. 1764
  7. 2475
  8. 336
  9. 11449
  10. 100
  11. 384
  12. 169
  13. 109
  14. 2704
  15. 5600
  16. 729
  17. 4445
  18. 1156
  19. 10
  20. 122
  21. 25
  22. 3136
  23. 4899
  24. 202
  25. 899
  26. 105
  27. 256
  28. 5625
  29. 5776
  30. 4624
  31. 1824
  32. 6084
  33. 396
  34. 20
  35. 39
  36. 49
  37. 712
  38. 5329
  39. 3599
  40. 44

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