Linearly Dependent Question

[ahamdiheme]

1. The problem statement, all variables and given/known data
Suppose v_1,...,v_k is a linearly dependent set. Then show that one of the vectors must be a linear combination of the others.

2. Relevant equations

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3. The attempt at a solution

I have attached an attempt at the problem. Thank you for help

[HallsofIvy]

Your solution says a_1v_1+ a_2v_2+ a_3v_3+ \cdot\cdot\cdot+ a_nv_n= 0 and then you go to v_1= (-1/a_1)(a_2v_2+ a_3v_3+ \cdot\cdot\cdot+ a_nv_n)

That's pretty good. The only problem is you don't know that a1 is not 0! If it is you can't solve for v1. What you DO know, from the definition of "dependent", that you didn't say is that at least one of the "ai" is NOT 0. You don't know which one but you can always say "Let "k" be such that ak is not 0". Then what?

[ahamdiheme]

Thank you. What if i say let k:ak not equal to 0
and v1 is a linear combination of v2,...,vn iff a1=ak

[Mark44]

You want to show that vk is a linear combination of the rest of the vectors. IOW, that vk is a linear combination of v1, v2, ..., vk-1, vk+1, ..., vn.

[ahamdiheme]

ok, i think i get it