For the composition table of a cyclic group shown below Which one of the…

2009

For the composition table of a cyclic group shown below

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Which one of the following choices is correct?

  1. A.

    a, b are generators

  2. B.

    b, c are generators

  3. C.

    c, d are generators

  4. D.

    d, a are generators

Attempted by 15 students.

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Correct answer: C

Solution:

Identify the identity element: The row labeled a has entries (a, b, c, d), so a acts as the identity (a * x = x and x * a = x).

  • Element b: b * b = a, so b has order 2 and cannot generate the whole group.

  • Element c: c * c = b, c^3 = d, c^4 = a, so c has order 4 and is a generator.

  • Element d: d * d = b, d^3 = c, d^4 = a, so d has order 4 and is a generator.

Conclusion: The elements of order 4 (the generators of this cyclic group) are c and d, so the correct choice names c and d as generators.

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