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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 239 · 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 48².
  2. 2.Use (a + b)(a − b) = a² − b² to find 44 × 36.
  3. 3.Use (a − b)² = a² − 2ab + b² to find 27².
  4. 4.Use (a + b)² = a² + 2ab + b² to find 37².
  5. 5.Use (a + b)² = a² + 2ab + b² to find 66².
  6. 6.Use (a + b)² = a² + 2ab + b² to find 11².
  7. 7.Use a² − b² = (a + b)(a − b) to find 75² − 31².
  8. 8.Use (a + b)(a − b) = a² − b² to find 27 × 13.
  9. 9.If a − b = 9 and ab = 22, what is a² + b²?
  10. 10.Use (a + b)(a − b) = a² − b² to find 39 × 21.
  11. 11.Use (a − b)² = a² − 2ab + b² to find 61².
  12. 12.Use (a + b)² = a² + 2ab + b² to find 22².
  13. 13.Use (a − b)² = a² − 2ab + b² to find 68².
  14. 14.Use (a − b)² = a² − 2ab + b² to find 23².
  15. 15.Use (a + b)² = a² + 2ab + b² to find 53².
  16. 16.If a − b = 1 and ab = 2, what is a² + b²?
  17. 17.Use (a + b)(a − b) = a² − b² to find 97 × 83.
  18. 18.Use a² − b² = (a + b)(a − b) to find 31² − 12².
  19. 19.Use a² − b² = (a + b)(a − b) to find 64² − 11².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 19².
  21. 21.If a − b = 3 and ab = 70, what is a² + b²?
  22. 22.Use (a + b)(a − b) = a² − b² to find 73 × 67.
  23. 23.Use (a − b)² = a² − 2ab + b² to find 53².
  24. 24.Find the value of x² + 2xy + y² when x = 5 and y = 3.
  25. 25.If a − b = 5 and ab = 84, what is a² + b²?
  26. 26.Use a² − b² = (a + b)(a − b) to find 37² − 14².
  27. 27.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  28. 28.Use (a + b)² = a² + 2ab + b² to find 52².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 106².
  30. 30.Use a² − b² = (a + b)(a − b) to find 55² − 36².
  31. 31.Use a² − b² = (a + b)(a − b) to find 80² − 26².
  32. 32.Use (a − b)² = a² − 2ab + b² to find 57².
  33. 33.Find the value of x² − 2xy + y² when x = 9 and y = 3.
  34. 34.If a + b = 15 and ab = 54, what is a² + b²?
  35. 35.Use (a + b)(a − b) = a² − b² to find 47 × 33.
  36. 36.Find the value of x² + 2xy + y² when x = 15 and y = 13.
  37. 37.Use (a + b)² = a² + 2ab + b² to find 32².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 76².
  39. 39.If a − b = 4 and ab = 5, what is a² + b²?
  40. 40.Use a² − b² = (a + b)(a − b) to find 91² − 41².

Answer key

  1. 2304
  2. 1584
  3. 729
  4. 1369
  5. 4356
  6. 121
  7. 4664
  8. 351
  9. 125
  10. 819
  11. 3721
  12. 484
  13. 4624
  14. 529
  15. 2809
  16. 5
  17. 8051
  18. 817
  19. 3975
  20. 361
  21. 149
  22. 4891
  23. 2809
  24. 64
  25. 193
  26. 1173
  27. 899
  28. 2704
  29. 11236
  30. 1729
  31. 5724
  32. 3249
  33. 36
  34. 117
  35. 1551
  36. 784
  37. 1024
  38. 5776
  39. 26
  40. 6600

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