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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 609 · 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.Find the value of x² + 2xy + y² when x = 8 and y = 1.
  2. 2.Use a² − b² = (a + b)(a − b) to find 24² − 2².
  3. 3.If a − b = 1 and ab = 90, what is a² + b²?
  4. 4.Use a² − b² = (a + b)(a − b) to find 29² − 13².
  5. 5.Find the value of x² − y² when x = 9 and y = 1.
  6. 6.Find the value of x² + 2xy + y² when x = 14 and y = 12.
  7. 7.Find the value of x² + 2xy + y² when x = 8 and y = 5.
  8. 8.Use (a + b)² = a² + 2ab + b² to find 85².
  9. 9.Use a² − b² = (a + b)(a − b) to find 61² − 18².
  10. 10.If a + b = 13 and ab = 40, what is a² + b²?
  11. 11.Use a² − b² = (a + b)(a − b) to find 97² − 75².
  12. 12.Use a² − b² = (a + b)(a − b) to find 82² − 79².
  13. 13.Use a² − b² = (a + b)(a − b) to find 23² − 10².
  14. 14.Use (a + b)(a − b) = a² − b² to find 81 × 79.
  15. 15.Find the value of x² − y² when x = 6 and y = 2.
  16. 16.Use (a + b)(a − b) = a² − b² to find 106 × 94.
  17. 17.Use (a + b)² = a² + 2ab + b² to find 34².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 27².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 35².
  20. 20.Use (a + b)² = a² + 2ab + b² to find 42².
  21. 21.Use a² − b² = (a + b)(a − b) to find 36² − 26².
  22. 22.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  23. 23.Use (a + b)² = a² + 2ab + b² to find 18².
  24. 24.Use a² − b² = (a + b)(a − b) to find 25² − 24².
  25. 25.Use (a + b)(a − b) = a² − b² to find 23 × 17.
  26. 26.Use (a + b)² = a² + 2ab + b² to find 27².
  27. 27.Use (a − b)² = a² − 2ab + b² to find 73².
  28. 28.Use (a − b)² = a² − 2ab + b² to find 82².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 12².
  30. 30.Use (a − b)² = a² − 2ab + b² to find 99².
  31. 31.Use (a + b)(a − b) = a² − b² to find 36 × 24.
  32. 32.Use a² − b² = (a + b)(a − b) to find 67² − 25².
  33. 33.Use (a + b)(a − b) = a² − b² to find 57 × 43.
  34. 34.Use (a − b)² = a² − 2ab + b² to find 61².
  35. 35.Find the value of x² − 2xy + y² when x = 10 and y = 4.
  36. 36.If a − b = 1 and ab = 2, what is a² + b²?
  37. 37.Use (a + b)² = a² + 2ab + b² to find 76².
  38. 38.Use a² − b² = (a + b)(a − b) to find 25² − 22².
  39. 39.Use (a + b)² = a² + 2ab + b² to find 14².
  40. 40.Use (a + b)(a − b) = a² − b² to find 62 × 58.

Answer key

  1. 81
  2. 572
  3. 181
  4. 672
  5. 80
  6. 676
  7. 169
  8. 7225
  9. 3397
  10. 89
  11. 3784
  12. 483
  13. 429
  14. 6399
  15. 32
  16. 9964
  17. 1156
  18. 729
  19. 1225
  20. 1764
  21. 620
  22. 899
  23. 324
  24. 49
  25. 391
  26. 729
  27. 5329
  28. 6724
  29. 144
  30. 9801
  31. 864
  32. 3864
  33. 2451
  34. 3721
  35. 36
  36. 5
  37. 5776
  38. 141
  39. 196
  40. 3596

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