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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 141 · 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)² = a² − 2ab + b² to find 88².
  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 39².
  4. 4.Find the value of x² + 2xy + y² when x = 11 and y = 8.
  5. 5.If a − b = 1 and ab = 6, what is a² + b²?
  6. 6.Use (a − b)² = a² − 2ab + b² to find 48².
  7. 7.Use (a − b)² = a² − 2ab + b² to find 75².
  8. 8.Use (a + b)² = a² + 2ab + b² to find 72².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 41².
  10. 10.Use (a + b)² = a² + 2ab + b² to find 104².
  11. 11.Use (a + b)(a − b) = a² − b² to find 83 × 77.
  12. 12.Use a² − b² = (a + b)(a − b) to find 42² − 4².
  13. 13.Use (a − b)² = a² − 2ab + b² to find 41².
  14. 14.Use (a + b)² = a² + 2ab + b² to find 93².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 95².
  16. 16.Use (a − b)² = a² − 2ab + b² to find 66².
  17. 17.Use (a + b)² = a² + 2ab + b² to find 52².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 57².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 48².
  20. 20.Use (a + b)(a − b) = a² − b² to find 41 × 39.
  21. 21.Use a² − b² = (a + b)(a − b) to find 72² − 34².
  22. 22.If a − b = 6 and ab = 16, what is a² + b²?
  23. 23.Use (a + b)(a − b) = a² − b² to find 63 × 57.
  24. 24.Use (a + b)(a − b) = a² − b² to find 65 × 55.
  25. 25.Use a² − b² = (a + b)(a − b) to find 43² − 31².
  26. 26.If a − b = 6 and ab = 27, what is a² + b²?
  27. 27.Use (a − b)² = a² − 2ab + b² to find 78².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 34².
  29. 29.Find the value of x² + 2xy + y² when x = 5 and y = 3.
  30. 30.Use (a + b)(a − b) = a² − b² to find 84 × 76.
  31. 31.Use (a + b)² = a² + 2ab + b² to find 92².
  32. 32.Use (a − b)² = a² − 2ab + b² to find 22².
  33. 33.Use a² − b² = (a + b)(a − b) to find 83² − 2².
  34. 34.Use a² − b² = (a + b)(a − b) to find 46² − 8².
  35. 35.Use (a − b)² = a² − 2ab + b² to find 37².
  36. 36.If a − b = 1 and ab = 2, what is a² + b²?
  37. 37.Use (a − b)² = a² − 2ab + b² to find 16².
  38. 38.Use (a + b)(a − b) = a² − b² to find 55 × 45.
  39. 39.Use (a − b)² = a² − 2ab + b² to find 26².
  40. 40.Use (a + b)² = a² + 2ab + b² to find 28².

Answer key

  1. 7744
  2. 9
  3. 1521
  4. 361
  5. 13
  6. 2304
  7. 5625
  8. 5184
  9. 1681
  10. 10816
  11. 6391
  12. 1748
  13. 1681
  14. 8649
  15. 9025
  16. 4356
  17. 2704
  18. 3249
  19. 2304
  20. 1599
  21. 4028
  22. 68
  23. 3591
  24. 3575
  25. 888
  26. 90
  27. 6084
  28. 1156
  29. 64
  30. 6384
  31. 8464
  32. 484
  33. 6885
  34. 2052
  35. 1369
  36. 5
  37. 256
  38. 2475
  39. 676
  40. 784

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