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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 370 · 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 51².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 82².
  3. 3.Use (a + b)² = a² + 2ab + b² to find 18².
  4. 4.Use (a + b)² = a² + 2ab + b² to find 87².
  5. 5.Use (a + b)(a − b) = a² − b² to find 59 × 41.
  6. 6.Use (a + b)(a − b) = a² − b² to find 83 × 77.
  7. 7.Use (a + b)(a − b) = a² − b² to find 26 × 14.
  8. 8.Use (a + b)(a − b) = a² − b² to find 44 × 36.
  9. 9.Use (a + b)(a − b) = a² − b² to find 29 × 11.
  10. 10.Use (a − b)² = a² − 2ab + b² to find 42².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 95².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 44².
  13. 13.Use (a + b)(a − b) = a² − b² to find 51 × 49.
  14. 14.Use a² − b² = (a + b)(a − b) to find 75² − 73².
  15. 15.Find the value of x² + 2xy + y² when x = 11 and y = 8.
  16. 16.Use (a + b)² = a² + 2ab + b² to find 42².
  17. 17.If a + b = 3 and ab = 2, what is a² + b²?
  18. 18.Use (a − b)² = a² − 2ab + b² to find 61².
  19. 19.If a + b = 12 and ab = 35, what is a² + b²?
  20. 20.Use (a + b)² = a² + 2ab + b² to find 63².
  21. 21.Use a² − b² = (a + b)(a − b) to find 72² − 28².
  22. 22.Use (a + b)(a − b) = a² − b² to find 37 × 23.
  23. 23.Find the value of x² − 2xy + y² when x = 10 and y = 8.
  24. 24.Use (a + b)(a − b) = a² − b² to find 72 × 68.
  25. 25.Use a² − b² = (a + b)(a − b) to find 28² − 9².
  26. 26.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  27. 27.Find the value of x² + 2xy + y² when x = 7 and y = 5.
  28. 28.Use (a + b)(a − b) = a² − b² to find 57 × 43.
  29. 29.If a + b = 8 and ab = 15, what is a² + b²?
  30. 30.Use (a − b)² = a² − 2ab + b² to find 63².
  31. 31.Use (a + b)² = a² + 2ab + b² to find 26².
  32. 32.Use (a − b)² = a² − 2ab + b² to find 39².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 72².
  34. 34.Use a² − b² = (a + b)(a − b) to find 55² − 29².
  35. 35.Use (a − b)² = a² − 2ab + b² to find 66².
  36. 36.If a − b = 3 and ab = 54, what is a² + b²?
  37. 37.If a − b = 6 and ab = 40, what is a² + b²?
  38. 38.Find the value of x² − 2xy + y² when x = 7 and y = 6.
  39. 39.Use a² − b² = (a + b)(a − b) to find 25² − 24².
  40. 40.Find the value of x² − 2xy + y² when x = 15 and y = 3.

Answer key

  1. 2601
  2. 6724
  3. 324
  4. 7569
  5. 2419
  6. 6391
  7. 364
  8. 1584
  9. 319
  10. 1764
  11. 9025
  12. 1936
  13. 2499
  14. 296
  15. 361
  16. 1764
  17. 5
  18. 3721
  19. 74
  20. 3969
  21. 4400
  22. 851
  23. 4
  24. 4896
  25. 703
  26. 875
  27. 144
  28. 2451
  29. 34
  30. 3969
  31. 676
  32. 1521
  33. 5184
  34. 2184
  35. 4356
  36. 117
  37. 116
  38. 1
  39. 49
  40. 144

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