Extend the functional by continuity (Functional analysis)

mathdunce
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Homework Statement



Let E be a dense linear subspace of a normed vector space X, and let Y be a
Banach space. Suppose T0 \in £(E, Y) is a bounded linear operator from E to Y.
Show that T0 can be extended to T\in £(E, Y) (by continuity) without increasing its norm.

The Attempt at a Solution


Someone kindly gave me a hint. I am trying to work out the details. The deadline is approaching. So I put the question here just in case. Thanks.
For this particular problem you want to show that if (xn) converges to x then T0(xn) is a Cauchy sequence and then define f(x) as the limit of the sequence. Finally you need to show that the map is a well-defined bounded linear function.
 
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Use that T0 is uniform continuous.
 
Thank you!
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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