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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 108 · 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 92².
  2. 2.Use a² − b² = (a + b)(a − b) to find 27² − 4².
  3. 3.If a + b = 14 and ab = 40, what is a² + b²?
  4. 4.Use (a − b)² = a² − 2ab + b² to find 12².
  5. 5.Use (a − b)² = a² − 2ab + b² to find 44².
  6. 6.Use (a + b)² = a² + 2ab + b² to find 15².
  7. 7.Use (a + b)(a − b) = a² − b² to find 47 × 33.
  8. 8.Use (a + b)² = a² + 2ab + b² to find 55².
  9. 9.Use (a + b)² = a² + 2ab + b² to find 82².
  10. 10.Use (a − b)² = a² − 2ab + b² to find 48².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 87².
  12. 12.If a + b = 6 and ab = 5, what is a² + b²?
  13. 13.Find the value of x² + 2xy + y² when x = 4 and y = 3.
  14. 14.Use (a − b)² = a² − 2ab + b² to find 73².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 15².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 36².
  17. 17.Find the value of x² − y² when x = 6 and y = 5.
  18. 18.Find the value of x² + 2xy + y² when x = 14 and y = 2.
  19. 19.Use (a + b)(a − b) = a² − b² to find 67 × 53.
  20. 20.Use a² − b² = (a + b)(a − b) to find 63² − 11².
  21. 21.If a + b = 14 and ab = 24, what is a² + b²?
  22. 22.Use (a + b)(a − b) = a² − b² to find 99 × 81.
  23. 23.Use a² − b² = (a + b)(a − b) to find 39² − 7².
  24. 24.Use a² − b² = (a + b)(a − b) to find 83² − 72².
  25. 25.Use (a − b)² = a² − 2ab + b² to find 78².
  26. 26.Use a² − b² = (a + b)(a − b) to find 29² − 23².
  27. 27.Find the value of x² + 2xy + y² when x = 7 and y = 2.
  28. 28.Use a² − b² = (a + b)(a − b) to find 31² − 10².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 96².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 56².
  31. 31.Use a² − b² = (a + b)(a − b) to find 54² − 35².
  32. 32.Find the value of x² − y² when x = 4 and y = 2.
  33. 33.Use (a − b)² = a² − 2ab + b² to find 47².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 76².
  35. 35.Use (a + b)² = a² + 2ab + b² to find 46².
  36. 36.Use (a − b)² = a² − 2ab + b² to find 24².
  37. 37.If a + b = 16 and ab = 60, what is a² + b²?
  38. 38.Use (a − b)² = a² − 2ab + b² to find 19².
  39. 39.If a + b = 11 and ab = 30, what is a² + b²?
  40. 40.Find the value of x² + 2xy + y² when x = 10 and y = 4.

Answer key

  1. 8464
  2. 713
  3. 116
  4. 144
  5. 1936
  6. 225
  7. 1551
  8. 3025
  9. 6724
  10. 2304
  11. 7569
  12. 26
  13. 49
  14. 5329
  15. 225
  16. 1296
  17. 11
  18. 256
  19. 3551
  20. 3848
  21. 148
  22. 8019
  23. 1472
  24. 1705
  25. 6084
  26. 312
  27. 81
  28. 861
  29. 9216
  30. 3136
  31. 1691
  32. 12
  33. 2209
  34. 5776
  35. 2116
  36. 576
  37. 136
  38. 361
  39. 61
  40. 196

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