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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 556 · 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 a² − b² = (a + b)(a − b) to find 60² − 53².
  2. 2.Find the value of x² + 2xy + y² when x = 7 and y = 1.
  3. 3.Use (a + b)(a − b) = a² − b² to find 22 × 18.
  4. 4.If a + b = 12 and ab = 20, what is a² + b²?
  5. 5.Use a² − b² = (a + b)(a − b) to find 31² − 7².
  6. 6.Use (a + b)² = a² + 2ab + b² to find 81².
  7. 7.Use (a − b)² = a² − 2ab + b² to find 59².
  8. 8.Find the value of x² − y² when x = 10 and y = 8.
  9. 9.Use (a + b)² = a² + 2ab + b² to find 56².
  10. 10.Use (a + b)(a − b) = a² − b² to find 104 × 96.
  11. 11.Use (a + b)² = a² + 2ab + b² to find 95².
  12. 12.Find the value of x² − 2xy + y² when x = 11 and y = 8.
  13. 13.If a − b = 3 and ab = 54, what is a² + b²?
  14. 14.Use (a − b)² = a² − 2ab + b² to find 98².
  15. 15.Find the value of x² + 2xy + y² when x = 9 and y = 4.
  16. 16.Use (a − b)² = a² − 2ab + b² to find 61².
  17. 17.Use a² − b² = (a + b)(a − b) to find 99² − 69².
  18. 18.If a − b = 3 and ab = 4, what is a² + b²?
  19. 19.Use (a + b)(a − b) = a² − b² to find 21 × 19.
  20. 20.Use (a − b)² = a² − 2ab + b² to find 45².
  21. 21.Find the value of x² − y² when x = 12 and y = 1.
  22. 22.Use (a − b)² = a² − 2ab + b² to find 35².
  23. 23.Use (a + b)(a − b) = a² − b² to find 82 × 78.
  24. 24.Use (a − b)² = a² − 2ab + b² to find 72².
  25. 25.Use (a − b)² = a² − 2ab + b² to find 88².
  26. 26.Use (a + b)(a − b) = a² − b² to find 36 × 24.
  27. 27.Use a² − b² = (a + b)(a − b) to find 63² − 46².
  28. 28.Use a² − b² = (a + b)(a − b) to find 79² − 26².
  29. 29.Use a² − b² = (a + b)(a − b) to find 31² − 18².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 35².
  31. 31.If a − b = 3 and ab = 10, what is a² + b²?
  32. 32.Use a² − b² = (a + b)(a − b) to find 34² − 2².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 84².
  34. 34.Find the value of x² − 2xy + y² when x = 12 and y = 4.
  35. 35.Use (a − b)² = a² − 2ab + b² to find 65².
  36. 36.Use (a − b)² = a² − 2ab + b² to find 71².
  37. 37.If a − b = 9 and ab = 10, what is a² + b²?
  38. 38.Use a² − b² = (a + b)(a − b) to find 56² − 22².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 108².
  40. 40.Use (a + b)(a − b) = a² − b² to find 87 × 73.

Answer key

  1. 791
  2. 64
  3. 396
  4. 104
  5. 912
  6. 6561
  7. 3481
  8. 36
  9. 3136
  10. 9984
  11. 9025
  12. 9
  13. 117
  14. 9604
  15. 169
  16. 3721
  17. 5040
  18. 17
  19. 399
  20. 2025
  21. 143
  22. 1225
  23. 6396
  24. 5184
  25. 7744
  26. 864
  27. 1853
  28. 5565
  29. 637
  30. 1225
  31. 29
  32. 1152
  33. 7056
  34. 64
  35. 4225
  36. 5041
  37. 101
  38. 2652
  39. 11664
  40. 6351

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