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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 562 · 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 a² − b² = (a + b)(a − b) to find 70² − 67².
  2. 2.Use (a + b)(a − b) = a² − b² to find 34 × 26.
  3. 3.Use a² − b² = (a + b)(a − b) to find 98² − 14².
  4. 4.Find the value of x² + 2xy + y² when x = 10 and y = 5.
  5. 5.Use (a + b)² = a² + 2ab + b² to find 12².
  6. 6.If a − b = 2 and ab = 3, what is a² + b²?
  7. 7.Use a² − b² = (a + b)(a − b) to find 37² − 6².
  8. 8.If a − b = 1 and ab = 132, what is a² + b²?
  9. 9.If a − b = 7 and ab = 44, what is a² + b²?
  10. 10.If a + b = 13 and ab = 30, what is a² + b²?
  11. 11.If a + b = 10 and ab = 9, what is a² + b²?
  12. 12.Use (a + b)² = a² + 2ab + b² to find 63².
  13. 13.Use (a + b)(a − b) = a² − b² to find 25 × 15.
  14. 14.Find the value of x² − y² when x = 5 and y = 3.
  15. 15.Use (a − b)² = a² − 2ab + b² to find 76².
  16. 16.If a + b = 5 and ab = 6, what is a² + b²?
  17. 17.Use (a − b)² = a² − 2ab + b² to find 25².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 22².
  19. 19.If a + b = 8 and ab = 7, what is a² + b²?
  20. 20.Use (a + b)² = a² + 2ab + b² to find 76².
  21. 21.Use (a − b)² = a² − 2ab + b² to find 78².
  22. 22.Use (a − b)² = a² − 2ab + b² to find 51².
  23. 23.If a + b = 5 and ab = 4, what is a² + b²?
  24. 24.Use (a + b)(a − b) = a² − b² to find 49 × 31.
  25. 25.If a − b = 1 and ab = 2, what is a² + b²?
  26. 26.Find the value of x² + 2xy + y² when x = 14 and y = 5.
  27. 27.Use (a − b)² = a² − 2ab + b² to find 21².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 99².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 28².
  30. 30.Use a² − b² = (a + b)(a − b) to find 32² − 27².
  31. 31.Find the value of x² − y² when x = 14 and y = 13.
  32. 32.If a − b = 4 and ab = 60, what is a² + b²?
  33. 33.Use (a − b)² = a² − 2ab + b² to find 61².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 62².
  35. 35.Use (a − b)² = a² − 2ab + b² to find 19².
  36. 36.Use a² − b² = (a + b)(a − b) to find 58² − 16².
  37. 37.Use (a + b)² = a² + 2ab + b² to find 45².
  38. 38.Use (a + b)² = a² + 2ab + b² to find 65².
  39. 39.Find the value of x² + 2xy + y² when x = 6 and y = 5.
  40. 40.Use (a − b)² = a² − 2ab + b² to find 46².

Answer key

  1. 411
  2. 884
  3. 9408
  4. 225
  5. 144
  6. 10
  7. 1333
  8. 265
  9. 137
  10. 109
  11. 82
  12. 3969
  13. 375
  14. 16
  15. 5776
  16. 13
  17. 625
  18. 484
  19. 50
  20. 5776
  21. 6084
  22. 2601
  23. 17
  24. 1519
  25. 5
  26. 361
  27. 441
  28. 9801
  29. 784
  30. 295
  31. 27
  32. 136
  33. 3721
  34. 3844
  35. 361
  36. 3108
  37. 2025
  38. 4225
  39. 121
  40. 2116

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