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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 968 · 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.If a − b = 5 and ab = 6, what is a² + b²?
  2. 2.Find the value of x² − y² when x = 4 and y = 3.
  3. 3.Use a² − b² = (a + b)(a − b) to find 99² − 85².
  4. 4.Use (a + b)² = a² + 2ab + b² to find 106².
  5. 5.Use (a − b)² = a² − 2ab + b² to find 49².
  6. 6.Use (a − b)² = a² − 2ab + b² to find 37².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 13².
  8. 8.Use (a + b)(a − b) = a² − b² to find 58 × 42.
  9. 9.Use (a − b)² = a² − 2ab + b² to find 78².
  10. 10.Find the value of x² − y² when x = 13 and y = 9.
  11. 11.Use (a − b)² = a² − 2ab + b² to find 54².
  12. 12.Use (a − b)² = a² − 2ab + b² to find 28².
  13. 13.If a + b = 17 and ab = 66, what is a² + b²?
  14. 14.Use a² − b² = (a + b)(a − b) to find 29² − 24².
  15. 15.If a + b = 18 and ab = 72, what is a² + b²?
  16. 16.Use (a − b)² = a² − 2ab + b² to find 52².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 83².
  18. 18.If a + b = 15 and ab = 50, what is a² + b²?
  19. 19.If a + b = 3 and ab = 2, what is a² + b²?
  20. 20.Use (a + b)² = a² + 2ab + b² to find 22².
  21. 21.Use (a + b)² = a² + 2ab + b² to find 84².
  22. 22.Use (a − b)² = a² − 2ab + b² to find 76².
  23. 23.Use (a − b)² = a² − 2ab + b² to find 88².
  24. 24.Use a² − b² = (a + b)(a − b) to find 96² − 66².
  25. 25.Use (a + b)² = a² + 2ab + b² to find 69².
  26. 26.If a − b = 6 and ab = 16, what is a² + b²?
  27. 27.Use (a + b)² = a² + 2ab + b² to find 107².
  28. 28.Use (a + b)(a − b) = a² − b² to find 94 × 86.
  29. 29.Use (a + b)² = a² + 2ab + b² to find 14².
  30. 30.Use (a − b)² = a² − 2ab + b² to find 38².
  31. 31.Use (a + b)(a − b) = a² − b² to find 45 × 35.
  32. 32.Use (a + b)(a − b) = a² − b² to find 21 × 19.
  33. 33.Use a² − b² = (a + b)(a − b) to find 34² − 12².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 98².
  35. 35.Use (a − b)² = a² − 2ab + b² to find 47².
  36. 36.Use (a − b)² = a² − 2ab + b² to find 13².
  37. 37.Find the value of x² + 2xy + y² when x = 4 and y = 1.
  38. 38.If a − b = 3 and ab = 54, what is a² + b²?
  39. 39.Use a² − b² = (a + b)(a − b) to find 26² − 17².
  40. 40.Use a² − b² = (a + b)(a − b) to find 42² − 26².

Answer key

  1. 37
  2. 7
  3. 2576
  4. 11236
  5. 2401
  6. 1369
  7. 169
  8. 2436
  9. 6084
  10. 88
  11. 2916
  12. 784
  13. 157
  14. 265
  15. 180
  16. 2704
  17. 6889
  18. 125
  19. 5
  20. 484
  21. 7056
  22. 5776
  23. 7744
  24. 4860
  25. 4761
  26. 68
  27. 11449
  28. 8084
  29. 196
  30. 1444
  31. 1575
  32. 399
  33. 1012
  34. 9604
  35. 2209
  36. 169
  37. 25
  38. 117
  39. 387
  40. 1088

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