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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 262 · 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.Find the value of x² − y² when x = 3 and y = 1.
  2. 2.Use (a − b)² = a² − 2ab + b² to find 86².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 11².
  4. 4.Find the value of x² − 2xy + y² when x = 5 and y = 1.
  5. 5.Use (a + b)² = a² + 2ab + b² to find 28².
  6. 6.Use (a + b)² = a² + 2ab + b² to find 74².
  7. 7.Use a² − b² = (a + b)(a − b) to find 35² − 25².
  8. 8.If a + b = 13 and ab = 12, what is a² + b²?
  9. 9.Use (a + b)² = a² + 2ab + b² to find 31².
  10. 10.Use a² − b² = (a + b)(a − b) to find 30² − 25².
  11. 11.Use (a + b)² = a² + 2ab + b² to find 53².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 45².
  13. 13.Use (a + b)² = a² + 2ab + b² to find 64².
  14. 14.Use (a + b)(a − b) = a² − b² to find 83 × 77.
  15. 15.Find the value of x² − 2xy + y² when x = 10 and y = 8.
  16. 16.Find the value of x² − y² when x = 8 and y = 6.
  17. 17.Use (a − b)² = a² − 2ab + b² to find 52².
  18. 18.Use (a + b)(a − b) = a² − b² to find 79 × 61.
  19. 19.Use (a + b)(a − b) = a² − b² to find 91 × 89.
  20. 20.Find the value of x² + 2xy + y² when x = 11 and y = 2.
  21. 21.If a − b = 4 and ab = 96, what is a² + b²?
  22. 22.Use a² − b² = (a + b)(a − b) to find 87² − 14².
  23. 23.Use a² − b² = (a + b)(a − b) to find 39² − 1².
  24. 24.Use a² − b² = (a + b)(a − b) to find 84² − 54².
  25. 25.Find the value of x² − y² when x = 11 and y = 1.
  26. 26.If a − b = 1 and ab = 6, what is a² + b²?
  27. 27.Use (a + b)² = a² + 2ab + b² to find 101².
  28. 28.Use (a + b)(a − b) = a² − b² to find 63 × 57.
  29. 29.Use (a − b)² = a² − 2ab + b² to find 38².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 88².
  31. 31.Use a² − b² = (a + b)(a − b) to find 37² − 33².
  32. 32.Use (a + b)(a − b) = a² − b² to find 72 × 68.
  33. 33.Use a² − b² = (a + b)(a − b) to find 71² − 35².
  34. 34.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  35. 35.Find the value of x² − y² when x = 10 and y = 4.
  36. 36.Use (a + b)² = a² + 2ab + b² to find 99².
  37. 37.Use a² − b² = (a + b)(a − b) to find 51² − 22².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 43².
  39. 39.Use (a − b)² = a² − 2ab + b² to find 68².
  40. 40.Use (a + b)² = a² + 2ab + b² to find 17².

Answer key

  1. 8
  2. 7396
  3. 121
  4. 16
  5. 784
  6. 5476
  7. 600
  8. 145
  9. 961
  10. 275
  11. 2809
  12. 2025
  13. 4096
  14. 6391
  15. 4
  16. 28
  17. 2704
  18. 4819
  19. 8099
  20. 169
  21. 208
  22. 7373
  23. 1520
  24. 4140
  25. 120
  26. 13
  27. 10201
  28. 3591
  29. 1444
  30. 7744
  31. 280
  32. 4896
  33. 3816
  34. 25
  35. 84
  36. 9801
  37. 2117
  38. 1849
  39. 4624
  40. 289

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