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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 789 · 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.Find the value of x² − 2xy + y² when x = 14 and y = 1.
  2. 2.Find the value of x² − y² when x = 7 and y = 6.
  3. 3.Use (a + b)² = a² + 2ab + b² to find 67².
  4. 4.Use (a + b)(a − b) = a² − b² to find 47 × 33.
  5. 5.Use a² − b² = (a + b)(a − b) to find 41² − 18².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 62².
  7. 7.Use (a + b)(a − b) = a² − b² to find 71 × 69.
  8. 8.Find the value of x² + 2xy + y² when x = 10 and y = 3.
  9. 9.Use (a + b)² = a² + 2ab + b² to find 81².
  10. 10.If a + b = 9 and ab = 14, what is a² + b²?
  11. 11.Use a² − b² = (a + b)(a − b) to find 43² − 3².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 68².
  13. 13.Find the value of x² + 2xy + y² when x = 5 and y = 3.
  14. 14.Use (a − b)² = a² − 2ab + b² to find 92².
  15. 15.Use (a + b)² = a² + 2ab + b² to find 76².
  16. 16.Use (a − b)² = a² − 2ab + b² to find 26².
  17. 17.If a + b = 15 and ab = 50, what is a² + b²?
  18. 18.Use a² − b² = (a + b)(a − b) to find 25² − 22².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 48².
  20. 20.Use (a + b)(a − b) = a² − b² to find 28 × 12.
  21. 21.If a + b = 3 and ab = 2, what is a² + b²?
  22. 22.Use (a + b)² = a² + 2ab + b² to find 21².
  23. 23.If a − b = 6 and ab = 7, what is a² + b²?
  24. 24.If a + b = 4 and ab = 3, what is a² + b²?
  25. 25.Use a² − b² = (a + b)(a − b) to find 90² − 82².
  26. 26.Use (a + b)² = a² + 2ab + b² to find 98².
  27. 27.Use a² − b² = (a + b)(a − b) to find 66² − 35².
  28. 28.Find the value of x² − 2xy + y² when x = 14 and y = 4.
  29. 29.Use a² − b² = (a + b)(a − b) to find 32² − 1².
  30. 30.Find the value of x² − 2xy + y² when x = 5 and y = 2.
  31. 31.Find the value of x² − y² when x = 3 and y = 1.
  32. 32.If a − b = 2 and ab = 3, what is a² + b²?
  33. 33.Use a² − b² = (a + b)(a − b) to find 34² − 26².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 38².
  35. 35.Use (a + b)² = a² + 2ab + b² to find 87².
  36. 36.Find the value of x² − y² when x = 4 and y = 2.
  37. 37.Use (a + b)(a − b) = a² − b² to find 76 × 64.
  38. 38.Use (a + b)² = a² + 2ab + b² to find 63².
  39. 39.Use a² − b² = (a + b)(a − b) to find 23² − 1².
  40. 40.Use (a + b)² = a² + 2ab + b² to find 71².

Answer key

  1. 169
  2. 13
  3. 4489
  4. 1551
  5. 1357
  6. 3844
  7. 4899
  8. 169
  9. 6561
  10. 53
  11. 1840
  12. 4624
  13. 64
  14. 8464
  15. 5776
  16. 676
  17. 125
  18. 141
  19. 2304
  20. 336
  21. 5
  22. 441
  23. 50
  24. 10
  25. 1376
  26. 9604
  27. 3131
  28. 100
  29. 1023
  30. 9
  31. 8
  32. 10
  33. 480
  34. 1444
  35. 7569
  36. 12
  37. 4864
  38. 3969
  39. 528
  40. 5041

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