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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 345 · 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 35².
  2. 2.Use (a + b)² = a² + 2ab + b² to find 47².
  3. 3.Use (a − b)² = a² − 2ab + b² to find 36².
  4. 4.If a + b = 15 and ab = 54, what is a² + b²?
  5. 5.Use (a + b)² = a² + 2ab + b² to find 39².
  6. 6.Use (a + b)² = a² + 2ab + b² to find 55².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 34².
  8. 8.Find the value of x² − y² when x = 15 and y = 9.
  9. 9.Use a² − b² = (a + b)(a − b) to find 42² − 32².
  10. 10.Use (a + b)² = a² + 2ab + b² to find 22².
  11. 11.Use (a − b)² = a² − 2ab + b² to find 39².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 43².
  13. 13.Use (a + b)(a − b) = a² − b² to find 52 × 48.
  14. 14.Use (a − b)² = a² − 2ab + b² to find 24².
  15. 15.Use (a + b)(a − b) = a² − b² to find 32 × 28.
  16. 16.If a + b = 11 and ab = 10, what is a² + b²?
  17. 17.If a + b = 6 and ab = 8, what is a² + b²?
  18. 18.Find the value of x² − y² when x = 3 and y = 1.
  19. 19.Use a² − b² = (a + b)(a − b) to find 60² − 38².
  20. 20.Use a² − b² = (a + b)(a − b) to find 74² − 1².
  21. 21.Use (a + b)(a − b) = a² − b² to find 69 × 51.
  22. 22.If a + b = 9 and ab = 14, what is a² + b²?
  23. 23.Use (a − b)² = a² − 2ab + b² to find 16².
  24. 24.Use (a − b)² = a² − 2ab + b² to find 82².
  25. 25.Use (a + b)² = a² + 2ab + b² to find 67².
  26. 26.Use (a − b)² = a² − 2ab + b² to find 67².
  27. 27.Use a² − b² = (a + b)(a − b) to find 44² − 39².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 92².
  29. 29.Find the value of x² − 2xy + y² when x = 13 and y = 9.
  30. 30.Use (a − b)² = a² − 2ab + b² to find 92².
  31. 31.Use (a + b)² = a² + 2ab + b² to find 15².
  32. 32.Find the value of x² − y² when x = 7 and y = 6.
  33. 33.Use a² − b² = (a + b)(a − b) to find 72² − 14².
  34. 34.Use (a + b)(a − b) = a² − b² to find 74 × 66.
  35. 35.Find the value of x² + 2xy + y² when x = 4 and y = 2.
  36. 36.If a − b = 1 and ab = 56, what is a² + b²?
  37. 37.Use a² − b² = (a + b)(a − b) to find 24² − 11².
  38. 38.Use a² − b² = (a + b)(a − b) to find 74² − 57².
  39. 39.Use (a − b)² = a² − 2ab + b² to find 99².
  40. 40.Use (a + b)² = a² + 2ab + b² to find 38².

Answer key

  1. 1225
  2. 2209
  3. 1296
  4. 117
  5. 1521
  6. 3025
  7. 1156
  8. 144
  9. 740
  10. 484
  11. 1521
  12. 1849
  13. 2496
  14. 576
  15. 896
  16. 101
  17. 20
  18. 8
  19. 2156
  20. 5475
  21. 3519
  22. 53
  23. 256
  24. 6724
  25. 4489
  26. 4489
  27. 415
  28. 8464
  29. 16
  30. 8464
  31. 225
  32. 13
  33. 4988
  34. 4884
  35. 36
  36. 113
  37. 455
  38. 2227
  39. 9801
  40. 1444

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