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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 545 · 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 54².
  2. 2.Use (a + b)(a − b) = a² − b² to find 87 × 73.
  3. 3.Use a² − b² = (a + b)(a − b) to find 56² − 45².
  4. 4.Use a² − b² = (a + b)(a − b) to find 27² − 2².
  5. 5.Use a² − b² = (a + b)(a − b) to find 67² − 12².
  6. 6.Use a² − b² = (a + b)(a − b) to find 97² − 11².
  7. 7.Find the value of x² − 2xy + y² when x = 10 and y = 9.
  8. 8.Use (a + b)(a − b) = a² − b² to find 44 × 36.
  9. 9.Use (a + b)(a − b) = a² − b² to find 92 × 88.
  10. 10.Use (a + b)(a − b) = a² − b² to find 64 × 56.
  11. 11.Use a² − b² = (a + b)(a − b) to find 70² − 32².
  12. 12.If a + b = 13 and ab = 40, what is a² + b²?
  13. 13.Use (a − b)² = a² − 2ab + b² to find 91².
  14. 14.If a − b = 4 and ab = 5, what is a² + b²?
  15. 15.Find the value of x² + 2xy + y² when x = 7 and y = 6.
  16. 16.Find the value of x² + 2xy + y² when x = 13 and y = 11.
  17. 17.Use (a + b)(a − b) = a² − b² to find 48 × 32.
  18. 18.Use (a − b)² = a² − 2ab + b² to find 56².
  19. 19.Use (a + b)² = a² + 2ab + b² to find 102².
  20. 20.Find the value of x² − y² when x = 13 and y = 2.
  21. 21.Use (a − b)² = a² − 2ab + b² to find 49².
  22. 22.Use a² − b² = (a + b)(a − b) to find 24² − 11².
  23. 23.Find the value of x² + 2xy + y² when x = 11 and y = 3.
  24. 24.Use (a + b)² = a² + 2ab + b² to find 41².
  25. 25.Use (a + b)² = a² + 2ab + b² to find 27².
  26. 26.If a + b = 4 and ab = 3, what is a² + b²?
  27. 27.Find the value of x² + 2xy + y² when x = 8 and y = 4.
  28. 28.Use a² − b² = (a + b)(a − b) to find 81² − 1².
  29. 29.If a + b = 6 and ab = 8, what is a² + b²?
  30. 30.Use a² − b² = (a + b)(a − b) to find 89² − 25².
  31. 31.Use (a + b)² = a² + 2ab + b² to find 44².
  32. 32.Use (a + b)² = a² + 2ab + b² to find 33².
  33. 33.Use (a + b)² = a² + 2ab + b² to find 22².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 67².
  35. 35.Use (a − b)² = a² − 2ab + b² to find 43².
  36. 36.Use (a + b)(a − b) = a² − b² to find 69 × 51.
  37. 37.Use a² − b² = (a + b)(a − b) to find 40² − 18².
  38. 38.Use (a + b)(a − b) = a² − b² to find 43 × 37.
  39. 39.Use (a + b)² = a² + 2ab + b² to find 92².
  40. 40.Use (a + b)(a − b) = a² − b² to find 51 × 49.

Answer key

  1. 2916
  2. 6351
  3. 1111
  4. 725
  5. 4345
  6. 9288
  7. 1
  8. 1584
  9. 8096
  10. 3584
  11. 3876
  12. 89
  13. 8281
  14. 26
  15. 169
  16. 576
  17. 1536
  18. 3136
  19. 10404
  20. 165
  21. 2401
  22. 455
  23. 196
  24. 1681
  25. 729
  26. 10
  27. 144
  28. 6560
  29. 20
  30. 7296
  31. 1936
  32. 1089
  33. 484
  34. 4489
  35. 1849
  36. 3519
  37. 1276
  38. 1591
  39. 8464
  40. 2499

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