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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 804 · 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 31 × 29.
  2. 2.Find the value of x² − 2xy + y² when x = 4 and y = 1.
  3. 3.Use (a − b)² = a² − 2ab + b² to find 13².
  4. 4.Use (a − b)² = a² − 2ab + b² to find 29².
  5. 5.Use a² − b² = (a + b)(a − b) to find 45² − 9².
  6. 6.Find the value of x² − 2xy + y² when x = 9 and y = 7.
  7. 7.Use a² − b² = (a + b)(a − b) to find 71² − 46².
  8. 8.Find the value of x² − 2xy + y² when x = 5 and y = 4.
  9. 9.If a + b = 17 and ab = 72, what is a² + b²?
  10. 10.Use (a − b)² = a² − 2ab + b² to find 81².
  11. 11.Use a² − b² = (a + b)(a − b) to find 96² − 6².
  12. 12.Find the value of x² − 2xy + y² when x = 3 and y = 2.
  13. 13.If a − b = 11 and ab = 12, what is a² + b²?
  14. 14.If a + b = 3 and ab = 2, what is a² + b²?
  15. 15.Find the value of x² + 2xy + y² when x = 4 and y = 3.
  16. 16.Use a² − b² = (a + b)(a − b) to find 25² − 5².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 13².
  18. 18.Use (a + b)² = a² + 2ab + b² to find 67².
  19. 19.Use (a + b)(a − b) = a² − b² to find 37 × 23.
  20. 20.Find the value of x² + 2xy + y² when x = 14 and y = 3.
  21. 21.Use (a + b)(a − b) = a² − b² to find 51 × 49.
  22. 22.Use a² − b² = (a + b)(a − b) to find 43² − 36².
  23. 23.Use a² − b² = (a + b)(a − b) to find 37² − 32².
  24. 24.Use (a + b)² = a² + 2ab + b² to find 93².
  25. 25.Use a² − b² = (a + b)(a − b) to find 57² − 7².
  26. 26.Use a² − b² = (a + b)(a − b) to find 79² − 12².
  27. 27.Use (a − b)² = a² − 2ab + b² to find 83².
  28. 28.Use a² − b² = (a + b)(a − b) to find 85² − 27².
  29. 29.Find the value of x² + 2xy + y² when x = 6 and y = 3.
  30. 30.Use (a + b)² = a² + 2ab + b² to find 92².
  31. 31.Use (a + b)(a − b) = a² − b² to find 93 × 87.
  32. 32.Find the value of x² − y² when x = 9 and y = 5.
  33. 33.Use (a + b)(a − b) = a² − b² to find 44 × 36.
  34. 34.Use (a − b)² = a² − 2ab + b² to find 88².
  35. 35.Use (a + b)(a − b) = a² − b² to find 71 × 69.
  36. 36.If a + b = 14 and ab = 48, what is a² + b²?
  37. 37.Use (a − b)² = a² − 2ab + b² to find 46².
  38. 38.Use a² − b² = (a + b)(a − b) to find 70² − 10².
  39. 39.Use (a + b)(a − b) = a² − b² to find 24 × 16.
  40. 40.Find the value of x² − y² when x = 15 and y = 13.

Answer key

  1. 899
  2. 9
  3. 169
  4. 841
  5. 1944
  6. 4
  7. 2925
  8. 1
  9. 145
  10. 6561
  11. 9180
  12. 1
  13. 145
  14. 5
  15. 49
  16. 600
  17. 169
  18. 4489
  19. 851
  20. 289
  21. 2499
  22. 553
  23. 345
  24. 8649
  25. 3200
  26. 6097
  27. 6889
  28. 6496
  29. 81
  30. 8464
  31. 8091
  32. 56
  33. 1584
  34. 7744
  35. 4899
  36. 100
  37. 2116
  38. 4800
  39. 384
  40. 56

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