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Linear Algebra Problem: Projections?

I don't really understand what this is saying, and how to prove it.

A linear mapping T: V -> V is called a projection if every element in w in the image is fixed by T. (That is, T(w) = w).

a) Let T be a projection. Prove that every v in V can be written as v = w+n with w in W and n in the nullspace of T.

b) Prove also that this expression is unique. That is, if v = w + n and v = w' + n' with w, w' in the image and n, n' in the nullspace, then w = w' and n = n'.

My professor pretty much through up the idea of the whole T: V -> V thing and I don't understand it at all especially where the w's come into play, and a little explanation of what exactly is going on would be appreciated.

Thanks

Update:

So the n and n' are = 0 because they are in the null space correct?

2 Answers

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  • 1 decade ago
    Favorite Answer

    a) T(w+n)=(=-because of liner transform )=T(w)=>w+T(n)=>0==w+0=w.

    b)T(w+n)=T(w'+n')

    T(w)+T(n)=T(w')+T(n')

    w+0=w'+0

    w=w'

    generally all transforms have an image and/or kernel ,and the her job is to moves vectors from subspaces or spaces w' is just a vector even if you don't know how it look like or you can call it x in f(x) so ( f==T )

  • 5 years ago

    so, how about an answer to e) and f) anybody

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