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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 952 · 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.If a − b = 7 and ab = 44, what is a² + b²?
  2. 2.Use (a − b)² = a² − 2ab + b² to find 49².
  3. 3.If a − b = 2 and ab = 3, what is a² + b²?
  4. 4.Use (a − b)² = a² − 2ab + b² to find 46².
  5. 5.Use (a − b)² = a² − 2ab + b² to find 91².
  6. 6.Use (a + b)(a − b) = a² − b² to find 73 × 67.
  7. 7.Use (a + b)(a − b) = a² − b² to find 26 × 14.
  8. 8.Use (a + b)(a − b) = a² − b² to find 21 × 19.
  9. 9.Use (a + b)² = a² + 2ab + b² to find 85².
  10. 10.Use a² − b² = (a + b)(a − b) to find 56² − 37².
  11. 11.If a − b = 1 and ab = 2, what is a² + b²?
  12. 12.Use a² − b² = (a + b)(a − b) to find 52² − 11².
  13. 13.Find the value of x² + 2xy + y² when x = 5 and y = 4.
  14. 14.Find the value of x² − y² when x = 7 and y = 5.
  15. 15.Use a² − b² = (a + b)(a − b) to find 23² − 17².
  16. 16.Use a² − b² = (a + b)(a − b) to find 65² − 12².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 25².
  18. 18.If a − b = 2 and ab = 8, what is a² + b²?
  19. 19.Use a² − b² = (a + b)(a − b) to find 98² − 14².
  20. 20.If a − b = 10 and ab = 11, what is a² + b²?
  21. 21.Use (a + b)² = a² + 2ab + b² to find 37².
  22. 22.Use (a + b)² = a² + 2ab + b² to find 11².
  23. 23.Use a² − b² = (a + b)(a − b) to find 59² − 24².
  24. 24.Find the value of x² + 2xy + y² when x = 12 and y = 8.
  25. 25.If a − b = 5 and ab = 36, what is a² + b²?
  26. 26.Use (a + b)(a − b) = a² − b² to find 42 × 38.
  27. 27.Use (a + b)(a − b) = a² − b² to find 32 × 28.
  28. 28.Use a² − b² = (a + b)(a − b) to find 36² − 10².
  29. 29.Use (a − b)² = a² − 2ab + b² to find 78².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 97².
  31. 31.Use (a + b)(a − b) = a² − b² to find 93 × 87.
  32. 32.Use (a + b)(a − b) = a² − b² to find 89 × 71.
  33. 33.Find the value of x² − 2xy + y² when x = 7 and y = 2.
  34. 34.Use (a − b)² = a² − 2ab + b² to find 51².
  35. 35.Use (a + b)² = a² + 2ab + b² to find 64².
  36. 36.Use (a + b)(a − b) = a² − b² to find 49 × 31.
  37. 37.Use (a + b)(a − b) = a² − b² to find 41 × 39.
  38. 38.If a − b = 1 and ab = 42, what is a² + b²?
  39. 39.Find the value of x² − y² when x = 4 and y = 2.
  40. 40.Use (a + b)² = a² + 2ab + b² to find 73².

Answer key

  1. 137
  2. 2401
  3. 10
  4. 2116
  5. 8281
  6. 4891
  7. 364
  8. 399
  9. 7225
  10. 1767
  11. 5
  12. 2583
  13. 81
  14. 24
  15. 240
  16. 4081
  17. 625
  18. 20
  19. 9408
  20. 122
  21. 1369
  22. 121
  23. 2905
  24. 400
  25. 97
  26. 1596
  27. 896
  28. 1196
  29. 6084
  30. 9409
  31. 8091
  32. 6319
  33. 25
  34. 2601
  35. 4096
  36. 1519
  37. 1599
  38. 85
  39. 12
  40. 5329

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