[Math] Which of the following are true about the ring of continuous real valued functions C[0,1]

abstract-algebraring-theory

Let $C[0,1]$ be the space of continuous real-valued functions on the interval $[0,1]$. This is a ring under point-wise addition and multiplication. Which of the following are true:

(a) For any $x ∈ [0,1]$, the ideal $M (x) = \{f ∈ C[0, 1] : f (x) = 0\}$ is maximal.

(b) $C[0, 1]$ is an integral domain.

(c) The group of units of $C[0, 1]$ is cyclic.

(d) The linear functions form a vector-space basis of $C[0, 1]$ over $\mathbb R$.

i know a statement is true because it is for any x not $every x$ therefore (a) is maximal ideal.

Because space is of real continuous real valued functions therefore (b) is true. I don't know how to prove or disprove (c) (d). thanx in advance

Best Answer

a),b) and d) have been treated in the comments. For c) you should notice that the constant functions give you a natural inclusion $\mathbb R^* \subset C[0,1]^*$ and $\mathbb R^* = \mathbb R \setminus \{0\}$ is not even countable, in particular not cyclic.

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