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drawar
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Homework Statement
The function [itex]h: \mathbb{R} \to \mathbb{R}[/itex] is continuous on [itex]\mathbb{R}[/itex] and let [itex]h(\mathbb{R})=\left\{ {h(x):x \in \mathbb{R}} \right\}[/itex] be the range of [itex]h[/itex]. Prove that if [itex]h(\mathbb{R})[/itex] is not bounded above and not bounded below, then [itex]h(\mathbb{R})=\mathbb{R}[/itex]
Homework Equations
The Attempt at a Solution
Well, this problem sounds so intuitive I don't know how to prove it. The only thing I can write down here is there exists a [itex]M > 0[/itex] s.t [itex]|h(x)|> M[/itex] for all real [itex]x[/itex].