Is it right to say that this is a group homomorphism and it only contains the trivial kernel?
$$\Phi : (\mathbb{R}\setminus\{0\}, ×) \longrightarrow (\mathbb{R}\setminus\{0\}, ×) : x \mapsto |x|$$
Is it right to say that this is a group homomorphism and it only contains the trivial kernel?
$$\Phi : (\mathbb{R}\setminus\{0\}, ×) \longrightarrow (\mathbb{R}\setminus\{0\}, ×) : x \mapsto |x|$$
It is a homomorphism. But the kernel is not trivial, since $1$ and $(-1)$ are both in the kernel.