Question

Prove or disprove that u(20) and u(24) are isomorphic

Answer 1

Explanation:

Thanks for the hint. I know that for two groups G and H to be isomorphic each group must have a subgroup of the same order. The cyclic subgroup generated by some element of order n in U(20), where n does not equal 2, will be of order n. Thus, U(24) and U(20) are not isomorphic. –