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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 527 · 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 68².
  2. 2.Use (a − b)² = a² − 2ab + b² to find 82².
  3. 3.Find the value of x² + 2xy + y² when x = 12 and y = 6.
  4. 4.Use (a + b)(a − b) = a² − b² to find 99 × 81.
  5. 5.Use (a + b)(a − b) = a² − b² to find 74 × 66.
  6. 6.Use (a − b)² = a² − 2ab + b² to find 48².
  7. 7.Find the value of x² − 2xy + y² when x = 14 and y = 11.
  8. 8.If a + b = 6 and ab = 8, what is a² + b²?
  9. 9.Use (a + b)² = a² + 2ab + b² to find 89².
  10. 10.Use (a + b)(a − b) = a² − b² to find 77 × 63.
  11. 11.Find the value of x² − y² when x = 15 and y = 11.
  12. 12.Use a² − b² = (a + b)(a − b) to find 37² − 14².
  13. 13.Use (a − b)² = a² − 2ab + b² to find 16².
  14. 14.Use a² − b² = (a + b)(a − b) to find 91² − 18².
  15. 15.Use (a + b)² = a² + 2ab + b² to find 36².
  16. 16.Use (a − b)² = a² − 2ab + b² to find 15².
  17. 17.If a − b = 1 and ab = 2, what is a² + b²?
  18. 18.Use (a + b)(a − b) = a² − b² to find 72 × 68.
  19. 19.Use (a − b)² = a² − 2ab + b² to find 58².
  20. 20.Use a² − b² = (a + b)(a − b) to find 95² − 78².
  21. 21.Use (a + b)(a − b) = a² − b² to find 95 × 85.
  22. 22.Use a² − b² = (a + b)(a − b) to find 34² − 27².
  23. 23.Use (a + b)² = a² + 2ab + b² to find 76².
  24. 24.Use a² − b² = (a + b)(a − b) to find 27² − 13².
  25. 25.Find the value of x² − 2xy + y² when x = 13 and y = 6.
  26. 26.If a + b = 16 and ab = 60, what is a² + b²?
  27. 27.Use (a + b)(a − b) = a² − b² to find 83 × 77.
  28. 28.Use (a + b)² = a² + 2ab + b² to find 22².
  29. 29.Use a² − b² = (a + b)(a − b) to find 74² − 7².
  30. 30.Use a² − b² = (a + b)(a − b) to find 62² − 26².
  31. 31.Use (a − b)² = a² − 2ab + b² to find 47².
  32. 32.If a − b = 5 and ab = 6, what is a² + b²?
  33. 33.Use (a + b)(a − b) = a² − b² to find 101 × 99.
  34. 34.If a − b = 2 and ab = 3, what is a² + b²?
  35. 35.Find the value of x² − y² when x = 12 and y = 8.
  36. 36.Use a² − b² = (a + b)(a − b) to find 52² − 37².
  37. 37.Find the value of x² + 2xy + y² when x = 15 and y = 4.
  38. 38.Use a² − b² = (a + b)(a − b) to find 62² − 30².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 53².
  40. 40.Use (a + b)(a − b) = a² − b² to find 73 × 67.

Answer key

  1. 4624
  2. 6724
  3. 324
  4. 8019
  5. 4884
  6. 2304
  7. 9
  8. 20
  9. 7921
  10. 4851
  11. 104
  12. 1173
  13. 256
  14. 7957
  15. 1296
  16. 225
  17. 5
  18. 4896
  19. 3364
  20. 2941
  21. 8075
  22. 427
  23. 5776
  24. 560
  25. 49
  26. 136
  27. 6391
  28. 484
  29. 5427
  30. 3168
  31. 2209
  32. 37
  33. 9999
  34. 10
  35. 80
  36. 1335
  37. 361
  38. 2944
  39. 2809
  40. 4891

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