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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 962 · 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 (a − b)² = a² − 2ab + b² to find 89².
  2. 2.Find the value of x² − y² when x = 8 and y = 5.
  3. 3.Find the value of x² − 2xy + y² when x = 8 and y = 6.
  4. 4.Use (a + b)² = a² + 2ab + b² to find 51².
  5. 5.Use a² − b² = (a + b)(a − b) to find 24² − 12².
  6. 6.Use (a + b)(a − b) = a² − b² to find 93 × 87.
  7. 7.Use (a − b)² = a² − 2ab + b² to find 25².
  8. 8.Use (a + b)² = a² + 2ab + b² to find 89².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 107².
  10. 10.Use a² − b² = (a + b)(a − b) to find 62² − 6².
  11. 11.Find the value of x² − y² when x = 15 and y = 12.
  12. 12.Use (a + b)(a − b) = a² − b² to find 48 × 32.
  13. 13.Find the value of x² + 2xy + y² when x = 9 and y = 1.
  14. 14.Find the value of x² − 2xy + y² when x = 10 and y = 2.
  15. 15.If a + b = 11 and ab = 10, what is a² + b²?
  16. 16.Use a² − b² = (a + b)(a − b) to find 80² − 51².
  17. 17.Use a² − b² = (a + b)(a − b) to find 68² − 20².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 11².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 11².
  20. 20.If a + b = 13 and ab = 40, what is a² + b²?
  21. 21.Use a² − b² = (a + b)(a − b) to find 71² − 3².
  22. 22.Use (a − b)² = a² − 2ab + b² to find 26².
  23. 23.If a + b = 16 and ab = 48, what is a² + b²?
  24. 24.Use (a + b)(a − b) = a² − b² to find 68 × 52.
  25. 25.Find the value of x² − 2xy + y² when x = 15 and y = 14.
  26. 26.Use (a + b)² = a² + 2ab + b² to find 94².
  27. 27.Find the value of x² − 2xy + y² when x = 13 and y = 5.
  28. 28.Find the value of x² − y² when x = 5 and y = 4.
  29. 29.Use a² − b² = (a + b)(a − b) to find 57² − 38².
  30. 30.Find the value of x² + 2xy + y² when x = 7 and y = 6.
  31. 31.Find the value of x² + 2xy + y² when x = 13 and y = 3.
  32. 32.Use (a − b)² = a² − 2ab + b² to find 14².
  33. 33.Use (a − b)² = a² − 2ab + b² to find 52².
  34. 34.Use (a − b)² = a² − 2ab + b² to find 88².
  35. 35.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  36. 36.Use (a + b)(a − b) = a² − b² to find 26 × 14.
  37. 37.Use (a + b)² = a² + 2ab + b² to find 65².
  38. 38.Use (a + b)(a − b) = a² − b² to find 21 × 19.
  39. 39.Use (a + b)(a − b) = a² − b² to find 102 × 98.
  40. 40.Find the value of x² − y² when x = 5 and y = 2.

Answer key

  1. 7921
  2. 39
  3. 4
  4. 2601
  5. 432
  6. 8091
  7. 625
  8. 7921
  9. 11449
  10. 3808
  11. 81
  12. 1536
  13. 100
  14. 64
  15. 101
  16. 3799
  17. 4224
  18. 121
  19. 121
  20. 89
  21. 5032
  22. 676
  23. 160
  24. 3536
  25. 1
  26. 8836
  27. 64
  28. 9
  29. 1805
  30. 169
  31. 256
  32. 196
  33. 2704
  34. 7744
  35. 899
  36. 364
  37. 4225
  38. 399
  39. 9996
  40. 21

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