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Continuous functions and dense subset proof...?
Let f and g be continuous functions from a metric space X into a metric space Y. Let S be a dense subset of X. Prove that f(S) is dense in f(X).
How should I approach this? Thank you.
3 Answers
- 8 years agoFavorite Answer
Hi A A,
You have to show that i) every point in f(X) is either in f(S) or ii) is a limit point of f(S). In the following, assume that y is in f(X) and f(x) = y:
i) If x is in S, the f(x) is in f(S)
ii) Suppose x is a limit point of S. The idea is that since there is a sequence of points x_n in X that tend to x, the sequence of points f(x_n) tends to f(x) because of continuity.
Hope that helps!
Daniel
- Anonymous5 years ago
My expensive fellowd192e0c4ad64a9c35fe32972477e4cd8 typically an unlimited dimensional vector area does no longer have a organic topology on it. What topology are you pondering on C[d192e0c4ad64a9c35fe32972477e4cd8d192e0c4ad64a9c35fe32972477e4cd8d192e0c4ad64a9c35fe32972477e4cd8]? then again: what's the area between applications you're speaking about? :-(
- EugeneLv 78 years ago
Since S is dense in X, cl(S) = X, where cl() denotes closure. Since f is continuous, f(cl(S)) ⊂ cl(f(S)), i.e., f(X) ⊂ cl(f(S)). Hence f(S) is dense in f(X).