# Vector space

Let [a,b] be an interval in {see attachment}. Recall that the set of functions {see attachment} is a vector space over {see attachment} with addition (f+g)(x):=f(x)+g(x) and scalar multiplication

a) choose [a,b]=[0,1]. Decide for each of the following subsets if it is a subspace. Justify your answer by giving a proof or a counterexample: {see attachment}

b) choose [a,b]=[ ]. Show that f(x) = sinx and g(x)=cosx are linearly independent.

?Let u and v be two vectors in a vector space v over {see attachment} . Denote, as usual, by span{u,v} the set of all linear combinations of these two vectors. Show that {see attachment}

https://brainmass.com/math/vector-calculus/vector-space-subsets-and-subspaces-25840

#### Solution Preview

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1.a)

(1) Let A={f: f(1)=0}

First (f+g)(1)=f(1)+g(1) = 0+0=0, so (f+g) A

Secondly , so A

Therefore A is a subspace.

(2) Let B= {f: f(1)=2}

First (f+g)(1)=f(1)+g(1) = 2+2=4 , so (f+g) B, and therefore B is not a subspace because addition ...

#### Solution Summary

This shows how to determine if subsets are subspaces. Vector spaces are analyzed. A counter example is provided.