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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 887 · 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.Use a² − b² = (a + b)(a − b) to find 53² − 32².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 75².
  3. 3.Find the value of x² + 2xy + y² when x = 12 and y = 1.
  4. 4.Use (a + b)² = a² + 2ab + b² to find 51².
  5. 5.If a + b = 4 and ab = 3, what is a² + b²?
  6. 6.Find the value of x² − y² when x = 11 and y = 1.
  7. 7.Find the value of x² + 2xy + y² when x = 13 and y = 4.
  8. 8.Use (a + b)² = a² + 2ab + b² to find 54².
  9. 9.Find the value of x² − 2xy + y² when x = 14 and y = 8.
  10. 10.If a + b = 9 and ab = 18, what is a² + b²?
  11. 11.Use a² − b² = (a + b)(a − b) to find 23² − 5².
  12. 12.Find the value of x² − 2xy + y² when x = 10 and y = 4.
  13. 13.Use (a + b)² = a² + 2ab + b² to find 28².
  14. 14.Use (a + b)(a − b) = a² − b² to find 63 × 57.
  15. 15.Use (a + b)(a − b) = a² − b² to find 24 × 16.
  16. 16.If a − b = 1 and ab = 2, what is a² + b²?
  17. 17.Find the value of x² − y² when x = 4 and y = 2.
  18. 18.Use (a + b)(a − b) = a² − b² to find 45 × 35.
  19. 19.Use a² − b² = (a + b)(a − b) to find 64² − 19².
  20. 20.Use (a − b)² = a² − 2ab + b² to find 43².
  21. 21.Use (a + b)² = a² + 2ab + b² to find 34².
  22. 22.Use (a − b)² = a² − 2ab + b² to find 16².
  23. 23.Use (a + b)² = a² + 2ab + b² to find 76².
  24. 24.Use (a − b)² = a² − 2ab + b² to find 42².
  25. 25.If a + b = 10 and ab = 24, what is a² + b²?
  26. 26.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  27. 27.Use (a + b)² = a² + 2ab + b² to find 21².
  28. 28.If a − b = 6 and ab = 16, what is a² + b²?
  29. 29.Use (a + b)(a − b) = a² − b² to find 47 × 33.
  30. 30.Use (a + b)(a − b) = a² − b² to find 21 × 19.
  31. 31.Use (a + b)(a − b) = a² − b² to find 78 × 62.
  32. 32.Use (a − b)² = a² − 2ab + b² to find 35².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 91².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 71².
  35. 35.Use (a + b)² = a² + 2ab + b² to find 31².
  36. 36.Use a² − b² = (a + b)(a − b) to find 61² − 20².
  37. 37.Use (a + b)² = a² + 2ab + b² to find 78².
  38. 38.Use (a + b)² = a² + 2ab + b² to find 81².
  39. 39.Use a² − b² = (a + b)(a − b) to find 80² − 21².
  40. 40.Use (a − b)² = a² − 2ab + b² to find 97².

Answer key

  1. 1785
  2. 5625
  3. 169
  4. 2601
  5. 10
  6. 120
  7. 289
  8. 2916
  9. 36
  10. 45
  11. 504
  12. 36
  13. 784
  14. 3591
  15. 384
  16. 5
  17. 12
  18. 1575
  19. 3735
  20. 1849
  21. 1156
  22. 256
  23. 5776
  24. 1764
  25. 52
  26. 899
  27. 441
  28. 68
  29. 1551
  30. 399
  31. 4836
  32. 1225
  33. 8281
  34. 5041
  35. 961
  36. 3321
  37. 6084
  38. 6561
  39. 5959
  40. 9409

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