Let $R$ be the set of all functions from $\mathbb{R}$ to $\mathbb{R}$. Is $R$ a ring? If so, is it commutative, and does it have an identity?

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Can someone please tell me how this looks. Thanks in advance! $$(R,+)$$

Take $R(x)$ and $G(x) \in \mathbb{R}$ then, $R(x) + G(x) \in \mathbb{R}$ and $R$ is closed under addition.

Also, $0 + R(x) = R(x) \in \mathbb{R}$ is the identity, and $R(x) + (-R(x)) = 0 \in \mathbb{R}$ is the additive inverse.

  • $[R(x) + G(x)] + H(x) = R(x) + [G(x) + H(x)]$ implies $R$ is associative.

  • $ R(x) + G(x) = G(x) + R(x)$ implies $R$ is commutative.

Hence, $R$ is an abelian group.

$$(R,\times)$$

Take $R(x) \times G(x) = G(x) \times R(x)$ implies $R$ is associative, and $R(x) \times G(x) = R(x) \in \mathbb{R}$. Hence, $R$ contains the identity $1(=G(x)) \in \mathbb{R}$. Also, $R(x) \times G(x) = G(x) \times R(x) \in \mathbb{R}$ implies $R$ is commutative.

Then, $$R(x)[G(x) + H(x)] = R(x) \times G(x) + R(x) \times H(x)$$ and $$[G(x) + H(x)] \times R(x) = G(x) \times R(x) + H(x) \times R(x)$$

Hence, $R$ obeys the distributive laws, and therefore $R$ is a commutative ring with identity $1.$

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