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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 266 · 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 95².
  2. 2.Use (a − b)² = a² − 2ab + b² to find 73².
  3. 3.Use (a + b)² = a² + 2ab + b² to find 45².
  4. 4.If a − b = 3 and ab = 88, what is a² + b²?
  5. 5.Use (a − b)² = a² − 2ab + b² to find 21².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 16².
  7. 7.Use a² − b² = (a + b)(a − b) to find 46² − 36².
  8. 8.Use (a + b)² = a² + 2ab + b² to find 98².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 11².
  10. 10.Use a² − b² = (a + b)(a − b) to find 30² − 9².
  11. 11.Use (a + b)(a − b) = a² − b² to find 87 × 73.
  12. 12.If a + b = 12 and ab = 20, what is a² + b²?
  13. 13.If a + b = 17 and ab = 60, what is a² + b²?
  14. 14.Use (a + b)(a − b) = a² − b² to find 106 × 94.
  15. 15.Use (a − b)² = a² − 2ab + b² to find 38².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 38².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 25².
  18. 18.Use a² − b² = (a + b)(a − b) to find 22² − 16².
  19. 19.Use (a − b)² = a² − 2ab + b² to find 25².
  20. 20.Use (a + b)(a − b) = a² − b² to find 75 × 65.
  21. 21.Use (a + b)² = a² + 2ab + b² to find 15².
  22. 22.Use (a + b)(a − b) = a² − b² to find 89 × 71.
  23. 23.Use a² − b² = (a + b)(a − b) to find 77² − 34².
  24. 24.If a + b = 4 and ab = 3, what is a² + b²?
  25. 25.Find the value of x² − y² when x = 3 and y = 2.
  26. 26.Use (a + b)² = a² + 2ab + b² to find 78².
  27. 27.Use (a + b)(a − b) = a² − b² to find 46 × 34.
  28. 28.Use a² − b² = (a + b)(a − b) to find 23² − 8².
  29. 29.Use (a − b)² = a² − 2ab + b² to find 98².
  30. 30.Use (a − b)² = a² − 2ab + b² to find 24².
  31. 31.If a − b = 3 and ab = 4, what is a² + b²?
  32. 32.Use a² − b² = (a + b)(a − b) to find 76² − 35².
  33. 33.If a + b = 10 and ab = 9, what is a² + b²?
  34. 34.Find the value of x² − 2xy + y² when x = 7 and y = 5.
  35. 35.Use (a + b)² = a² + 2ab + b² to find 107².
  36. 36.Use (a + b)(a − b) = a² − b² to find 58 × 42.
  37. 37.If a − b = 5 and ab = 66, what is a² + b²?
  38. 38.Use (a − b)² = a² − 2ab + b² to find 39².
  39. 39.Use (a − b)² = a² − 2ab + b² to find 15².
  40. 40.If a − b = 1 and ab = 2, what is a² + b²?

Answer key

  1. 9025
  2. 5329
  3. 2025
  4. 185
  5. 441
  6. 256
  7. 820
  8. 9604
  9. 121
  10. 819
  11. 6351
  12. 104
  13. 169
  14. 9964
  15. 1444
  16. 1444
  17. 625
  18. 228
  19. 625
  20. 4875
  21. 225
  22. 6319
  23. 4773
  24. 10
  25. 5
  26. 6084
  27. 1564
  28. 465
  29. 9604
  30. 576
  31. 17
  32. 4551
  33. 82
  34. 4
  35. 11449
  36. 2436
  37. 157
  38. 1521
  39. 225
  40. 5

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