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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 35 · 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 + 2xy + y² when x = 8 and y = 2.
  2. 2.Use (a + b)(a − b) = a² − b² to find 87 × 73.
  3. 3.Use (a − b)² = a² − 2ab + b² to find 72².
  4. 4.Use (a + b)² = a² + 2ab + b² to find 86².
  5. 5.Use (a − b)² = a² − 2ab + b² to find 19².
  6. 6.Find the value of x² − y² when x = 14 and y = 8.
  7. 7.Use (a − b)² = a² − 2ab + b² to find 39².
  8. 8.Find the value of x² − 2xy + y² when x = 4 and y = 1.
  9. 9.Use (a − b)² = a² − 2ab + b² to find 17².
  10. 10.Use a² − b² = (a + b)(a − b) to find 35² − 2².
  11. 11.Use a² − b² = (a + b)(a − b) to find 34² − 32².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 24².
  13. 13.Use (a − b)² = a² − 2ab + b² to find 81².
  14. 14.Use (a − b)² = a² − 2ab + b² to find 45².
  15. 15.If a + b = 5 and ab = 4, what is a² + b²?
  16. 16.Use a² − b² = (a + b)(a − b) to find 70² − 27².
  17. 17.Find the value of x² − y² when x = 13 and y = 5.
  18. 18.If a + b = 21 and ab = 110, what is a² + b²?
  19. 19.Use a² − b² = (a + b)(a − b) to find 82² − 56².
  20. 20.If a + b = 9 and ab = 18, what is a² + b²?
  21. 21.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  22. 22.Use (a + b)(a − b) = a² − b² to find 42 × 38.
  23. 23.Use a² − b² = (a + b)(a − b) to find 93² − 63².
  24. 24.Use (a − b)² = a² − 2ab + b² to find 88².
  25. 25.Find the value of x² − 2xy + y² when x = 13 and y = 5.
  26. 26.Find the value of x² + 2xy + y² when x = 7 and y = 2.
  27. 27.Use (a − b)² = a² − 2ab + b² to find 74².
  28. 28.Use a² − b² = (a + b)(a − b) to find 57² − 47².
  29. 29.If a + b = 15 and ab = 54, what is a² + b²?
  30. 30.Use a² − b² = (a + b)(a − b) to find 22² − 12².
  31. 31.Use (a + b)(a − b) = a² − b² to find 44 × 36.
  32. 32.Find the value of x² + 2xy + y² when x = 4 and y = 2.
  33. 33.If a − b = 4 and ab = 12, what is a² + b²?
  34. 34.Use a² − b² = (a + b)(a − b) to find 49² − 10².
  35. 35.Use (a + b)(a − b) = a² − b² to find 47 × 33.
  36. 36.Use a² − b² = (a + b)(a − b) to find 99² − 80².
  37. 37.Use a² − b² = (a + b)(a − b) to find 96² − 38².
  38. 38.Use (a + b)² = a² + 2ab + b² to find 17².
  39. 39.If a − b = 1 and ab = 2, what is a² + b²?
  40. 40.Find the value of x² − y² when x = 3 and y = 2.

Answer key

  1. 100
  2. 6351
  3. 5184
  4. 7396
  5. 361
  6. 132
  7. 1521
  8. 9
  9. 289
  10. 1221
  11. 132
  12. 576
  13. 6561
  14. 2025
  15. 17
  16. 4171
  17. 144
  18. 221
  19. 3588
  20. 45
  21. 1591
  22. 1596
  23. 4680
  24. 7744
  25. 64
  26. 81
  27. 5476
  28. 1040
  29. 117
  30. 340
  31. 1584
  32. 36
  33. 40
  34. 2301
  35. 1551
  36. 3401
  37. 7772
  38. 289
  39. 5
  40. 5

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