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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 285 · 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 = 6 and y = 3.
  2. 2.Use a² − b² = (a + b)(a − b) to find 20² − 10².
  3. 3.Use (a + b)(a − b) = a² − b² to find 72 × 68.
  4. 4.Use (a + b)² = a² + 2ab + b² to find 22².
  5. 5.Use (a − b)² = a² − 2ab + b² to find 48².
  6. 6.Use a² − b² = (a + b)(a − b) to find 99² − 74².
  7. 7.If a + b = 5 and ab = 6, what is a² + b²?
  8. 8.Use (a + b)(a − b) = a² − b² to find 33 × 27.
  9. 9.Use (a + b)(a − b) = a² − b² to find 95 × 85.
  10. 10.Use (a + b)² = a² + 2ab + b² to find 102².
  11. 11.Find the value of x² − y² when x = 9 and y = 1.
  12. 12.If a + b = 12 and ab = 27, what is a² + b²?
  13. 13.Use (a + b)(a − b) = a² − b² to find 48 × 32.
  14. 14.Find the value of x² − y² when x = 9 and y = 5.
  15. 15.Use (a + b)² = a² + 2ab + b² to find 88².
  16. 16.If a − b = 2 and ab = 3, what is a² + b²?
  17. 17.Use (a − b)² = a² − 2ab + b² to find 29².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 54².
  19. 19.Use a² − b² = (a + b)(a − b) to find 96² − 14².
  20. 20.Find the value of x² − y² when x = 7 and y = 5.
  21. 21.Use (a − b)² = a² − 2ab + b² to find 88².
  22. 22.If a − b = 6 and ab = 27, what is a² + b²?
  23. 23.Use a² − b² = (a + b)(a − b) to find 55² − 34².
  24. 24.Find the value of x² + 2xy + y² when x = 7 and y = 4.
  25. 25.Use (a − b)² = a² − 2ab + b² to find 31².
  26. 26.Use (a − b)² = a² − 2ab + b² to find 66².
  27. 27.Use (a + b)(a − b) = a² − b² to find 89 × 71.
  28. 28.If a + b = 5 and ab = 4, what is a² + b²?
  29. 29.Use (a − b)² = a² − 2ab + b² to find 79².
  30. 30.If a + b = 9 and ab = 18, what is a² + b²?
  31. 31.Use a² − b² = (a + b)(a − b) to find 35² − 24².
  32. 32.Use (a + b)² = a² + 2ab + b² to find 54².
  33. 33.If a − b = 4 and ab = 60, what is a² + b²?
  34. 34.Use a² − b² = (a + b)(a − b) to find 40² − 37².
  35. 35.Find the value of x² − y² when x = 8 and y = 5.
  36. 36.Use a² − b² = (a + b)(a − b) to find 81² − 17².
  37. 37.Use a² − b² = (a + b)(a − b) to find 37² − 25².
  38. 38.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  39. 39.Find the value of x² − 2xy + y² when x = 10 and y = 3.
  40. 40.Find the value of x² − 2xy + y² when x = 3 and y = 2.

Answer key

  1. 27
  2. 300
  3. 4896
  4. 484
  5. 2304
  6. 4325
  7. 13
  8. 891
  9. 8075
  10. 10404
  11. 80
  12. 90
  13. 1536
  14. 56
  15. 7744
  16. 10
  17. 841
  18. 2916
  19. 9020
  20. 24
  21. 7744
  22. 90
  23. 1869
  24. 121
  25. 961
  26. 4356
  27. 6319
  28. 17
  29. 6241
  30. 45
  31. 649
  32. 2916
  33. 136
  34. 231
  35. 39
  36. 6272
  37. 744
  38. 899
  39. 49
  40. 1

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