Why do the reals fill the rationals with the absolute value?

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SUMMARY

The discussion clarifies that the real numbers, denoted as $\mathbb{R}$, are the completion of the metric space formed by the rational numbers, $\mathbb{Q}$, under the absolute value norm. This means that $\mathbb{R}$ "fills" $\mathbb{Q}$ in the sense of density and completeness. The concept of completion is fundamental in metric space theory, establishing that every metric space has a complete space that contains it, which in this case is the real numbers.

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evinda
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Hi! (Cool)

Could you explain me why $\mathbb{R}$ fills $\mathbb{Q}$ as for the norm absolute value? (Worried)
 
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What do you mean by $\Bbb R$ "fills" $\Bbb Q$? Do you mean to say that $\Bbb Q$ is dense in $\Bbb R$? Your question is void if you can't define the nonmathematical term "fill".
 
Hi,

I think you are asking why the reals are the complection of the metric space consisting on the rationals with the absolute value.

In essence, one can prove that every metric space has a complete space containing it, and we just name this complection the 'real numbers'.

Hope this can help you.
 

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