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

Which one of the following choices is correct?
- A.
a, b are generators
- B.
b, c are generators
- C.
c, d are generators
- D.
d, a are generators
Attempted by 15 students.
Show answer & explanation
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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