- #1

skyturnred

- 118

- 0

## Homework Statement

v1=[2 1 1 4 2]

v2=[-1 2 2 1 -1]

v3=[3 -2 1 -2 2]

v4=[4 1 4 3 3]

v5=[1 2 3 2 1]

Find if the system is linear dependent or independent. If it is dependent, express the last vector in the list (v5) as a combination of the preceding ones.

## Homework Equations

## The Attempt at a Solution

I am having trouble with this one. Using the definition of independence (c1V1+c2V2+...+cnVn=0), I get the following matrix:

a=[2 -1 3 4 1; 1 2 -2 1 2; 1 2 1 4 3; 4 1 -2 3 2; 2 -1 2 3 1]. When I find det(a), I find it to be 0. This means that the system has a non-trivial solution, right? And if so, that means that the system is linear dependent right? so then I take the same matrix as an augmented matrix with the final column ([1; 2; 3; 2; 1]) as being the augmented part, since it is equal to V5 and I am trying to express it as a combination of the others. Then I find rref. But when I find rref I get the following:

a(rref)=[2 0 0 1 0; 0 1 0 1 0; 0 0 1 1 0; 0 0 0 0 1], but looking at the very last row, the matrix is inconsistent. If it is inconsistent, there is no value for c1, c2, c3 and c4 that would equal V5. So where did I go wrong? I double checked all my steps so there must be a problem with my understanding.