General Lin. Alg. Span Question

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If a question asks "does v1, v2, v3 span R4"
can i just say no, regardless of what v1 v2 v3 is
because v1 v2 and v3 is just 3 dimensions while R4 needs 4 dimensions?
 
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hydralisks said:
If a question asks "does v1, v2, v3 span R4"
can i just say no, regardless of what v1 v2 v3 is
because v1 v2 and v3 is just 3 dimensions while R4 needs 4 dimensions?

I'm almost sure you're right on this.
 
Thanks!
 
Yes. If a set of vectors spans a space, then some subset of it forms a basis for the space. Since no subset of 3 vectors can span a four dimensional set, this set cannot span R4.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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