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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 326 · 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 33 × 27.
  2. 2.If a − b = 1 and ab = 2, what is a² + b²?
  3. 3.Use a² − b² = (a + b)(a − b) to find 27² − 1².
  4. 4.Use (a − b)² = a² − 2ab + b² to find 59².
  5. 5.Use (a + b)² = a² + 2ab + b² to find 32².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 35².
  7. 7.Use (a − b)² = a² − 2ab + b² to find 39².
  8. 8.Find the value of x² − y² when x = 6 and y = 1.
  9. 9.Use (a + b)² = a² + 2ab + b² to find 59².
  10. 10.Use a² − b² = (a + b)(a − b) to find 28² − 14².
  11. 11.Find the value of x² − y² when x = 8 and y = 3.
  12. 12.Find the value of x² − 2xy + y² when x = 12 and y = 8.
  13. 13.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  14. 14.Use (a − b)² = a² − 2ab + b² to find 54².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 25².
  16. 16.Find the value of x² − y² when x = 15 and y = 3.
  17. 17.Use (a − b)² = a² − 2ab + b² to find 17².
  18. 18.Use (a + b)(a − b) = a² − b² to find 97 × 83.
  19. 19.If a − b = 2 and ab = 3, what is a² + b²?
  20. 20.Use a² − b² = (a + b)(a − b) to find 61² − 15².
  21. 21.Use (a + b)(a − b) = a² − b² to find 57 × 43.
  22. 22.Use (a − b)² = a² − 2ab + b² to find 49².
  23. 23.Use (a + b)(a − b) = a² − b² to find 58 × 42.
  24. 24.Use a² − b² = (a + b)(a − b) to find 56² − 4².
  25. 25.Use (a + b)² = a² + 2ab + b² to find 106².
  26. 26.Use (a − b)² = a² − 2ab + b² to find 64².
  27. 27.If a + b = 5 and ab = 4, what is a² + b²?
  28. 28.Use (a − b)² = a² − 2ab + b² to find 26².
  29. 29.If a − b = 3 and ab = 10, what is a² + b²?
  30. 30.If a + b = 11 and ab = 18, what is a² + b²?
  31. 31.Use (a + b)(a − b) = a² − b² to find 48 × 32.
  32. 32.Use (a + b)(a − b) = a² − b² to find 41 × 39.
  33. 33.Find the value of x² + 2xy + y² when x = 13 and y = 7.
  34. 34.Find the value of x² + 2xy + y² when x = 9 and y = 3.
  35. 35.Find the value of x² − y² when x = 6 and y = 3.
  36. 36.Use (a + b)(a − b) = a² − b² to find 51 × 49.
  37. 37.Use (a + b)(a − b) = a² − b² to find 27 × 13.
  38. 38.Use (a + b)² = a² + 2ab + b² to find 51².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 61².
  40. 40.Use (a − b)² = a² − 2ab + b² to find 55².

Answer key

  1. 891
  2. 5
  3. 728
  4. 3481
  5. 1024
  6. 1225
  7. 1521
  8. 35
  9. 3481
  10. 588
  11. 55
  12. 16
  13. 875
  14. 2916
  15. 625
  16. 216
  17. 289
  18. 8051
  19. 10
  20. 3496
  21. 2451
  22. 2401
  23. 2436
  24. 3120
  25. 11236
  26. 4096
  27. 17
  28. 676
  29. 29
  30. 85
  31. 1536
  32. 1599
  33. 400
  34. 144
  35. 27
  36. 2499
  37. 351
  38. 2601
  39. 3721
  40. 3025

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