My other thread might be useful: http://www.mathhelpforum.com/math-he...subspaces.htmlLet . Suppose further that is a subsapce of spanned by vectors and , and is a subspace of spanned by .
Determine and .
Sifting and gives those two vectors. Hence .
Similarly .
Since we know that is a subspace of .
Therefore and .
Is this it? This question was worth 10 marks but my answer is remarkably small!