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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 201 · 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)(a − b) = a² − b² to find 22 × 18.
  2. 2.Use (a + b)(a − b) = a² − b² to find 61 × 59.
  3. 3.Use (a − b)² = a² − 2ab + b² to find 62².
  4. 4.Use a² − b² = (a + b)(a − b) to find 78² − 6².
  5. 5.Use (a + b)² = a² + 2ab + b² to find 75².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 87².
  7. 7.Use (a − b)² = a² − 2ab + b² to find 16².
  8. 8.Use (a + b)² = a² + 2ab + b² to find 93².
  9. 9.Use a² − b² = (a + b)(a − b) to find 31² − 11².
  10. 10.Use a² − b² = (a + b)(a − b) to find 69² − 12².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 31².
  12. 12.Use (a + b)(a − b) = a² − b² to find 63 × 57.
  13. 13.If a − b = 5 and ab = 14, what is a² + b²?
  14. 14.Use (a + b)(a − b) = a² − b² to find 21 × 19.
  15. 15.Use (a + b)(a − b) = a² − b² to find 57 × 43.
  16. 16.Use (a − b)² = a² − 2ab + b² to find 44².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 22².
  18. 18.Use (a + b)(a − b) = a² − b² to find 56 × 44.
  19. 19.If a + b = 10 and ab = 21, what is a² + b²?
  20. 20.Use a² − b² = (a + b)(a − b) to find 98² − 52².
  21. 21.Use a² − b² = (a + b)(a − b) to find 49² − 31².
  22. 22.Use a² − b² = (a + b)(a − b) to find 83² − 28².
  23. 23.Use (a − b)² = a² − 2ab + b² to find 37².
  24. 24.If a + b = 14 and ab = 48, what is a² + b²?
  25. 25.Use a² − b² = (a + b)(a − b) to find 95² − 43².
  26. 26.Find the value of x² − y² when x = 3 and y = 1.
  27. 27.Use (a − b)² = a² − 2ab + b² to find 67².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 89².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 59².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 61².
  31. 31.If a − b = 1 and ab = 20, what is a² + b²?
  32. 32.Use (a + b)(a − b) = a² − b² to find 97 × 83.
  33. 33.Use (a + b)(a − b) = a² − b² to find 84 × 76.
  34. 34.Find the value of x² − y² when x = 6 and y = 4.
  35. 35.Use (a + b)² = a² + 2ab + b² to find 62².
  36. 36.If a − b = 1 and ab = 30, what is a² + b²?
  37. 37.If a + b = 14 and ab = 40, what is a² + b²?
  38. 38.Find the value of x² − 2xy + y² when x = 14 and y = 1.
  39. 39.Use (a − b)² = a² − 2ab + b² to find 13².
  40. 40.Find the value of x² − 2xy + y² when x = 6 and y = 1.

Answer key

  1. 396
  2. 3599
  3. 3844
  4. 6048
  5. 5625
  6. 7569
  7. 256
  8. 8649
  9. 840
  10. 4617
  11. 961
  12. 3591
  13. 53
  14. 399
  15. 2451
  16. 1936
  17. 484
  18. 2464
  19. 58
  20. 6900
  21. 1440
  22. 6105
  23. 1369
  24. 100
  25. 7176
  26. 8
  27. 4489
  28. 7921
  29. 3481
  30. 3721
  31. 41
  32. 8051
  33. 6384
  34. 20
  35. 3844
  36. 61
  37. 116
  38. 169
  39. 169
  40. 25

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