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Showing V is the direct sum of W1 and W2

  1. Mar 11, 2013 #1
    Hi all,

    Say that I already know W1, W2 are both subspaces of a vector space V, W1∩W2={0}, and that dim(W1)+dim(W2)=dim(V)=n, can I thus conclude that V=W1+W2, namely V is the direct sum of W1 and W2?
  2. jcsd
  3. Mar 12, 2013 #2


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    Yes, because ##\dim(W1+W2) + \dim(W1 \cap W2) = \dim(W1) + \dim(W2)##.
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