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Homework Help: Linear Algebra- Spanning Sets

  1. Apr 1, 2010 #1
    1. The problem statement, all variables and given/known data
    Let {x1,x2,.....,xk} be a spanning set for a vector space V.
    a) if we add another vector, xk+1 to the set, will we still have a spanning set ? Explain


    2. Relevant equations



    3. The attempt at a solution

    I think 'yes', but I am not sure if my explanation is correct.
    It doesn't matter if they are independent or dependent, because we know that the first k vectors are independent and that's what we need to create a spanning set for V.
    If the kth+1 vector is independent, the set is going to span a bigger vector space, a vector space that includes V. So, it's going to be a spanning set for V regardless of xk+1

    Is my reasoning correct ?

    Thanks.
     
  2. jcsd
  3. Apr 1, 2010 #2

    radou

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    Homework Helper

    Yes, it doesn't matter if they're independent or not, the set which contains xk+1 still spans V. And you don't know if the first k vectors are independent, as a matter of fact. Suppose dimV < k, for example.
     
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