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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 706 · 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)² = a² − 2ab + b² to find 17².
  2. 2.Use (a − b)² = a² − 2ab + b² to find 75².
  3. 3.Use (a + b)(a − b) = a² − b² to find 58 × 42.
  4. 4.Use (a + b)² = a² + 2ab + b² to find 46².
  5. 5.Use a² − b² = (a + b)(a − b) to find 25² − 6².
  6. 6.Use (a + b)² = a² + 2ab + b² to find 23².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 94².
  8. 8.Use (a − b)² = a² − 2ab + b² to find 36².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 78².
  10. 10.Use (a + b)(a − b) = a² − b² to find 104 × 96.
  11. 11.Use a² − b² = (a + b)(a − b) to find 46² − 13².
  12. 12.Use a² − b² = (a + b)(a − b) to find 47² − 43².
  13. 13.Use (a − b)² = a² − 2ab + b² to find 77².
  14. 14.Find the value of x² − 2xy + y² when x = 12 and y = 1.
  15. 15.Find the value of x² + 2xy + y² when x = 4 and y = 3.
  16. 16.If a − b = 5 and ab = 6, what is a² + b²?
  17. 17.If a + b = 7 and ab = 12, what is a² + b²?
  18. 18.Use a² − b² = (a + b)(a − b) to find 47² − 44².
  19. 19.Use a² − b² = (a + b)(a − b) to find 73² − 1².
  20. 20.Find the value of x² + 2xy + y² when x = 7 and y = 5.
  21. 21.Use (a + b)² = a² + 2ab + b² to find 61².
  22. 22.Use (a + b)² = a² + 2ab + b² to find 92².
  23. 23.If a + b = 6 and ab = 8, what is a² + b²?
  24. 24.Use (a + b)(a − b) = a² − b² to find 62 × 58.
  25. 25.Use (a − b)² = a² − 2ab + b² to find 22².
  26. 26.Use (a + b)(a − b) = a² − b² to find 42 × 38.
  27. 27.Use (a − b)² = a² − 2ab + b² to find 48².
  28. 28.Use a² − b² = (a + b)(a − b) to find 75² − 34².
  29. 29.If a − b = 1 and ab = 20, what is a² + b²?
  30. 30.Find the value of x² + 2xy + y² when x = 3 and y = 1.
  31. 31.Use a² − b² = (a + b)(a − b) to find 79² − 34².
  32. 32.Use a² − b² = (a + b)(a − b) to find 53² − 15².
  33. 33.Use (a + b)(a − b) = a² − b² to find 73 × 67.
  34. 34.Use (a + b)² = a² + 2ab + b² to find 18².
  35. 35.If a + b = 3 and ab = 2, what is a² + b²?
  36. 36.Find the value of x² − 2xy + y² when x = 7 and y = 1.
  37. 37.Use (a + b)² = a² + 2ab + b² to find 51².
  38. 38.Use (a + b)(a − b) = a² − b² to find 65 × 55.
  39. 39.Use (a + b)² = a² + 2ab + b² to find 107².
  40. 40.Use (a − b)² = a² − 2ab + b² to find 28².

Answer key

  1. 289
  2. 5625
  3. 2436
  4. 2116
  5. 589
  6. 529
  7. 8836
  8. 1296
  9. 6084
  10. 9984
  11. 1947
  12. 360
  13. 5929
  14. 121
  15. 49
  16. 37
  17. 25
  18. 273
  19. 5328
  20. 144
  21. 3721
  22. 8464
  23. 20
  24. 3596
  25. 484
  26. 1596
  27. 2304
  28. 4469
  29. 41
  30. 16
  31. 5085
  32. 2584
  33. 4891
  34. 324
  35. 5
  36. 36
  37. 2601
  38. 3575
  39. 11449
  40. 784

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