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Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 547 · 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 77².
  2. 2.Use (a + b)(a − b) = a² − b² to find 106 × 94.
  3. 3.Find the value of x² − y² when x = 3 and y = 2.
  4. 4.Use (a + b)(a − b) = a² − b² to find 31 × 29.
  5. 5.If a − b = 1 and ab = 6, what is a² + b²?
  6. 6.Use (a + b)² = a² + 2ab + b² to find 36².
  7. 7.Use (a + b)² = a² + 2ab + b² to find 104².
  8. 8.Use (a + b)(a − b) = a² − b² to find 46 × 34.
  9. 9.Use (a − b)² = a² − 2ab + b² to find 47².
  10. 10.Use a² − b² = (a + b)(a − b) to find 61² − 30².
  11. 11.Use (a + b)(a − b) = a² − b² to find 35 × 25.
  12. 12.Use (a − b)² = a² − 2ab + b² to find 78².
  13. 13.Find the value of x² + 2xy + y² when x = 3 and y = 1.
  14. 14.Use (a − b)² = a² − 2ab + b² to find 91².
  15. 15.Use (a − b)² = a² − 2ab + b² to find 53².
  16. 16.Use (a + b)(a − b) = a² − b² to find 79 × 61.
  17. 17.Find the value of x² − 2xy + y² when x = 12 and y = 8.
  18. 18.Use (a + b)² = a² + 2ab + b² to find 18².
  19. 19.Find the value of x² + 2xy + y² when x = 5 and y = 4.
  20. 20.Use (a + b)² = a² + 2ab + b² to find 106².
  21. 21.Use (a + b)² = a² + 2ab + b² to find 89².
  22. 22.Use a² − b² = (a + b)(a − b) to find 47² − 28².
  23. 23.Use (a + b)(a − b) = a² − b² to find 49 × 31.
  24. 24.Use (a − b)² = a² − 2ab + b² to find 88².
  25. 25.Use (a + b)² = a² + 2ab + b² to find 57².
  26. 26.Use (a − b)² = a² − 2ab + b² to find 52².
  27. 27.Find the value of x² + 2xy + y² when x = 6 and y = 4.
  28. 28.Use (a + b)² = a² + 2ab + b² to find 42².
  29. 29.If a − b = 4 and ab = 96, what is a² + b²?
  30. 30.Use a² − b² = (a + b)(a − b) to find 33² − 26².
  31. 31.Use (a + b)(a − b) = a² − b² to find 67 × 53.
  32. 32.Find the value of x² + 2xy + y² when x = 5 and y = 2.
  33. 33.Use (a − b)² = a² − 2ab + b² to find 37².
  34. 34.Use (a + b)² = a² + 2ab + b² to find 26².
  35. 35.If a − b = 2 and ab = 3, what is a² + b²?
  36. 36.Use (a + b)² = a² + 2ab + b² to find 14².
  37. 37.Use (a − b)² = a² − 2ab + b² to find 12².
  38. 38.If a − b = 2 and ab = 35, what is a² + b²?
  39. 39.If a + b = 13 and ab = 12, what is a² + b²?
  40. 40.Use a² − b² = (a + b)(a − b) to find 27² − 14².

Answer key

  1. 5929
  2. 9964
  3. 5
  4. 899
  5. 13
  6. 1296
  7. 10816
  8. 1564
  9. 2209
  10. 2821
  11. 875
  12. 6084
  13. 16
  14. 8281
  15. 2809
  16. 4819
  17. 16
  18. 324
  19. 81
  20. 11236
  21. 7921
  22. 1425
  23. 1519
  24. 7744
  25. 3249
  26. 2704
  27. 100
  28. 1764
  29. 208
  30. 413
  31. 3551
  32. 49
  33. 1369
  34. 676
  35. 10
  36. 196
  37. 144
  38. 74
  39. 145
  40. 533

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