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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 827 · 40 sums
TalentJR

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 = 12 and ab = 27, what is a² + b²?
  2. 2.Use (a − b)² = a² − 2ab + b² to find 25².
  3. 3.Use a² − b² = (a + b)(a − b) to find 21² − 11².
  4. 4.Use (a + b)(a − b) = a² − b² to find 44 × 36.
  5. 5.Use (a + b)(a − b) = a² − b² to find 28 × 12.
  6. 6.Use (a − b)² = a² − 2ab + b² to find 61².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 34².
  8. 8.Use (a + b)² = a² + 2ab + b² to find 73².
  9. 9.Use (a − b)² = a² − 2ab + b² to find 21².
  10. 10.Use (a − b)² = a² − 2ab + b² to find 98².
  11. 11.Use (a + b)² = a² + 2ab + b² to find 52².
  12. 12.Use (a + b)² = a² + 2ab + b² to find 108².
  13. 13.If a + b = 14 and ab = 24, what is a² + b²?
  14. 14.Use (a − b)² = a² − 2ab + b² to find 23².
  15. 15.Find the value of x² − y² when x = 8 and y = 7.
  16. 16.Use (a − b)² = a² − 2ab + b² to find 91².
  17. 17.If a − b = 1 and ab = 2, what is a² + b²?
  18. 18.Use (a + b)(a − b) = a² − b² to find 26 × 14.
  19. 19.Find the value of x² − 2xy + y² when x = 12 and y = 11.
  20. 20.Find the value of x² − 2xy + y² when x = 7 and y = 1.
  21. 21.Use (a + b)(a − b) = a² − b² to find 29 × 11.
  22. 22.Use (a + b)(a − b) = a² − b² to find 99 × 81.
  23. 23.Use (a + b)² = a² + 2ab + b² to find 74².
  24. 24.If a − b = 2 and ab = 35, what is a² + b²?
  25. 25.Find the value of x² − y² when x = 4 and y = 1.
  26. 26.If a − b = 9 and ab = 10, what is a² + b²?
  27. 27.Use (a + b)² = a² + 2ab + b² to find 45².
  28. 28.Use (a − b)² = a² − 2ab + b² to find 66².
  29. 29.If a + b = 10 and ab = 24, what is a² + b²?
  30. 30.Use (a − b)² = a² − 2ab + b² to find 41².
  31. 31.Find the value of x² + 2xy + y² when x = 15 and y = 8.
  32. 32.Use a² − b² = (a + b)(a − b) to find 53² − 6².
  33. 33.If a − b = 5 and ab = 36, what is a² + b²?
  34. 34.Use (a + b)² = a² + 2ab + b² to find 54².
  35. 35.Find the value of x² + 2xy + y² when x = 3 and y = 2.
  36. 36.Use (a + b)(a − b) = a² − b² to find 59 × 41.
  37. 37.Use (a + b)² = a² + 2ab + b² to find 39².
  38. 38.Use (a + b)(a − b) = a² − b² to find 92 × 88.
  39. 39.Find the value of x² + 2xy + y² when x = 4 and y = 1.
  40. 40.Use (a − b)² = a² − 2ab + b² to find 62².

Answer key

  1. 90
  2. 625
  3. 320
  4. 1584
  5. 336
  6. 3721
  7. 1156
  8. 5329
  9. 441
  10. 9604
  11. 2704
  12. 11664
  13. 148
  14. 529
  15. 15
  16. 8281
  17. 5
  18. 364
  19. 1
  20. 36
  21. 319
  22. 8019
  23. 5476
  24. 74
  25. 15
  26. 101
  27. 2025
  28. 4356
  29. 52
  30. 1681
  31. 529
  32. 2773
  33. 97
  34. 2916
  35. 25
  36. 2419
  37. 1521
  38. 8096
  39. 25
  40. 3844

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