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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 942 · 40 sums
TalentJR

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 62².
  2. 2.Use (a + b)(a − b) = a² − b² to find 64 × 56.
  3. 3.Use (a + b)² = a² + 2ab + b² to find 22².
  4. 4.If a − b = 7 and ab = 30, what is a² + b²?
  5. 5.Use (a − b)² = a² − 2ab + b² to find 12².
  6. 6.If a + b = 16 and ab = 48, what is a² + b²?
  7. 7.Use (a + b)² = a² + 2ab + b² to find 91².
  8. 8.Use a² − b² = (a + b)(a − b) to find 41² − 25².
  9. 9.Use a² − b² = (a + b)(a − b) to find 79² − 4².
  10. 10.Find the value of x² − y² when x = 6 and y = 5.
  11. 11.Use (a + b)(a − b) = a² − b² to find 105 × 95.
  12. 12.Use a² − b² = (a + b)(a − b) to find 73² − 63².
  13. 13.Use (a + b)² = a² + 2ab + b² to find 92².
  14. 14.Use (a − b)² = a² − 2ab + b² to find 61².
  15. 15.Use (a + b)(a − b) = a² − b² to find 95 × 85.
  16. 16.Use (a − b)² = a² − 2ab + b² to find 33².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 53².
  18. 18.Find the value of x² − y² when x = 15 and y = 13.
  19. 19.Use (a − b)² = a² − 2ab + b² to find 51².
  20. 20.If a − b = 1 and ab = 12, what is a² + b²?
  21. 21.Use (a + b)² = a² + 2ab + b² to find 78².
  22. 22.If a + b = 3 and ab = 2, what is a² + b²?
  23. 23.Use (a − b)² = a² − 2ab + b² to find 43².
  24. 24.If a + b = 10 and ab = 16, what is a² + b²?
  25. 25.Use a² − b² = (a + b)(a − b) to find 83² − 34².
  26. 26.Find the value of x² − 2xy + y² when x = 14 and y = 2.
  27. 27.Use a² − b² = (a + b)(a − b) to find 53² − 22².
  28. 28.Find the value of x² − y² when x = 10 and y = 1.
  29. 29.Use a² − b² = (a + b)(a − b) to find 39² − 21².
  30. 30.If a + b = 5 and ab = 4, what is a² + b²?
  31. 31.Use (a + b)² = a² + 2ab + b² to find 36².
  32. 32.Use a² − b² = (a + b)(a − b) to find 65² − 33².
  33. 33.Use (a − b)² = a² − 2ab + b² to find 73².
  34. 34.Use (a − b)² = a² − 2ab + b² to find 83².
  35. 35.If a + b = 13 and ab = 30, what is a² + b²?
  36. 36.Use (a + b)(a − b) = a² − b² to find 39 × 21.
  37. 37.Use (a − b)² = a² − 2ab + b² to find 87².
  38. 38.Use (a − b)² = a² − 2ab + b² to find 39².
  39. 39.Use (a − b)² = a² − 2ab + b² to find 11².
  40. 40.Use (a + b)² = a² + 2ab + b² to find 67².

Answer key

  1. 3844
  2. 3584
  3. 484
  4. 109
  5. 144
  6. 160
  7. 8281
  8. 1056
  9. 6225
  10. 11
  11. 9975
  12. 1360
  13. 8464
  14. 3721
  15. 8075
  16. 1089
  17. 2809
  18. 56
  19. 2601
  20. 25
  21. 6084
  22. 5
  23. 1849
  24. 68
  25. 5733
  26. 144
  27. 2325
  28. 99
  29. 1080
  30. 17
  31. 1296
  32. 3136
  33. 5329
  34. 6889
  35. 109
  36. 819
  37. 7569
  38. 1521
  39. 121
  40. 4489

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