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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 2 · 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 = 1 and ab = 2, what is a² + b²?
  2. 2.Use (a + b)(a − b) = a² − b² to find 53 × 47.
  3. 3.Find the value of x² − 2xy + y² when x = 8 and y = 3.
  4. 4.Use a² − b² = (a + b)(a − b) to find 58² − 47².
  5. 5.Find the value of x² − 2xy + y² when x = 14 and y = 5.
  6. 6.Use (a + b)² = a² + 2ab + b² to find 38².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 109².
  8. 8.Use a² − b² = (a + b)(a − b) to find 46² − 43².
  9. 9.Use a² − b² = (a + b)(a − b) to find 52² − 15².
  10. 10.If a + b = 8 and ab = 7, what is a² + b²?
  11. 11.Find the value of x² − y² when x = 12 and y = 11.
  12. 12.Find the value of x² − y² when x = 5 and y = 3.
  13. 13.If a − b = 6 and ab = 16, what is a² + b²?
  14. 14.Use (a + b)² = a² + 2ab + b² to find 17².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 98².
  16. 16.Use (a + b)² = a² + 2ab + b² to find 32².
  17. 17.Use (a − b)² = a² − 2ab + b² to find 76².
  18. 18.Use (a − b)² = a² − 2ab + b² to find 46².
  19. 19.Use (a − b)² = a² − 2ab + b² to find 82².
  20. 20.Use a² − b² = (a + b)(a − b) to find 37² − 10².
  21. 21.Use (a + b)² = a² + 2ab + b² to find 88².
  22. 22.Use (a + b)(a − b) = a² − b² to find 64 × 56.
  23. 23.Use (a + b)² = a² + 2ab + b² to find 92².
  24. 24.Find the value of x² + 2xy + y² when x = 6 and y = 2.
  25. 25.If a + b = 5 and ab = 6, what is a² + b²?
  26. 26.If a − b = 5 and ab = 6, what is a² + b²?
  27. 27.Use (a + b)² = a² + 2ab + b² to find 107².
  28. 28.Use (a + b)² = a² + 2ab + b² to find 85².
  29. 29.Use (a + b)² = a² + 2ab + b² to find 12².
  30. 30.Use (a + b)² = a² + 2ab + b² to find 63².
  31. 31.If a − b = 6 and ab = 72, what is a² + b²?
  32. 32.Use (a − b)² = a² − 2ab + b² to find 29².
  33. 33.Use (a + b)(a − b) = a² − b² to find 101 × 99.
  34. 34.If a − b = 9 and ab = 36, what is a² + b²?
  35. 35.Use a² − b² = (a + b)(a − b) to find 99² − 12².
  36. 36.Use (a + b)² = a² + 2ab + b² to find 16².
  37. 37.Use (a + b)(a − b) = a² − b² to find 34 × 26.
  38. 38.Use (a − b)² = a² − 2ab + b² to find 37².
  39. 39.Use (a − b)² = a² − 2ab + b² to find 99².
  40. 40.Find the value of x² + 2xy + y² when x = 4 and y = 3.

Answer key

  1. 5
  2. 2491
  3. 25
  4. 1155
  5. 81
  6. 1444
  7. 11881
  8. 267
  9. 2479
  10. 50
  11. 23
  12. 16
  13. 68
  14. 289
  15. 9604
  16. 1024
  17. 5776
  18. 2116
  19. 6724
  20. 1269
  21. 7744
  22. 3584
  23. 8464
  24. 64
  25. 13
  26. 37
  27. 11449
  28. 7225
  29. 144
  30. 3969
  31. 180
  32. 841
  33. 9999
  34. 153
  35. 9657
  36. 256
  37. 884
  38. 1369
  39. 9801
  40. 49

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