Prove that group of order 203 is abelian.
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Is 203 prime ?. – Amr Nov 13 '16 at 18:50
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7 x 29 = 203 implies that it has subgroups of order 7 and of order 29 – janmarqz Nov 13 '16 at 18:56
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This is false, we can build non-abelian groups of order $203$ by taking a semidirect product of $\mathbb Z_7$ and $\mathbb Z_{29}$.
To show one exists you just need to exhibit a non trivial morphism $\mathbb Z_7\rightarrow Aut(\mathbb Z_{29})$.
Recall that $Aut(\mathbb Z_{29})\cong \mathbb Z_{29}^*\cong \mathbb Z_{28}$ ( the last one is because $29$ is prime).
Clearly the homomorphism $f:\mathbb Z_7\rightarrow \mathbb Z_{28}$ defined by $\overline x\mapsto \overline{4x}$ works.

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