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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 464 · 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)(a − b) = a² − b² to find 26 × 14.
  2. 2.Find the value of x² − 2xy + y² when x = 14 and y = 10.
  3. 3.Use (a − b)² = a² − 2ab + b² to find 32².
  4. 4.If a − b = 1 and ab = 6, what is a² + b²?
  5. 5.Use (a − b)² = a² − 2ab + b² to find 81².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 76².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 88².
  8. 8.Use (a + b)² = a² + 2ab + b² to find 85².
  9. 9.Use (a − b)² = a² − 2ab + b² to find 21².
  10. 10.If a − b = 2 and ab = 3, what is a² + b²?
  11. 11.Find the value of x² − y² when x = 13 and y = 5.
  12. 12.Use a² − b² = (a + b)(a − b) to find 75² − 27².
  13. 13.If a − b = 8 and ab = 33, what is a² + b²?
  14. 14.Use (a + b)(a − b) = a² − b² to find 89 × 71.
  15. 15.Use a² − b² = (a + b)(a − b) to find 73² − 41².
  16. 16.Use a² − b² = (a + b)(a − b) to find 42² − 33².
  17. 17.Use a² − b² = (a + b)(a − b) to find 94² − 23².
  18. 18.Use a² − b² = (a + b)(a − b) to find 70² − 1².
  19. 19.Use (a − b)² = a² − 2ab + b² to find 59².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 88².
  21. 21.Use (a − b)² = a² − 2ab + b² to find 26².
  22. 22.If a − b = 1 and ab = 2, what is a² + b²?
  23. 23.Use (a − b)² = a² − 2ab + b² to find 96².
  24. 24.Use a² − b² = (a + b)(a − b) to find 54² − 40².
  25. 25.Use a² − b² = (a + b)(a − b) to find 61² − 44².
  26. 26.Use (a − b)² = a² − 2ab + b² to find 78².
  27. 27.If a + b = 13 and ab = 36, what is a² + b²?
  28. 28.Find the value of x² − y² when x = 9 and y = 5.
  29. 29.If a + b = 6 and ab = 5, what is a² + b²?
  30. 30.Use (a + b)(a − b) = a² − b² to find 102 × 98.
  31. 31.Find the value of x² + 2xy + y² when x = 6 and y = 1.
  32. 32.Use a² − b² = (a + b)(a − b) to find 24² − 7².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 82².
  34. 34.Use (a − b)² = a² − 2ab + b² to find 43².
  35. 35.Use (a − b)² = a² − 2ab + b² to find 95².
  36. 36.Use (a + b)(a − b) = a² − b² to find 95 × 85.
  37. 37.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  38. 38.If a − b = 8 and ab = 20, what is a² + b²?
  39. 39.Use (a − b)² = a² − 2ab + b² to find 35².
  40. 40.Use (a − b)² = a² − 2ab + b² to find 75².

Answer key

  1. 364
  2. 16
  3. 1024
  4. 13
  5. 6561
  6. 5776
  7. 7744
  8. 7225
  9. 441
  10. 10
  11. 144
  12. 4896
  13. 130
  14. 6319
  15. 3648
  16. 675
  17. 8307
  18. 4899
  19. 3481
  20. 7744
  21. 676
  22. 5
  23. 9216
  24. 1316
  25. 1785
  26. 6084
  27. 97
  28. 56
  29. 26
  30. 9996
  31. 49
  32. 527
  33. 6724
  34. 1849
  35. 9025
  36. 8075
  37. 25
  38. 104
  39. 1225
  40. 5625

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