Solving Linear Dependence of a Matrix

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Homework Help Overview

The discussion revolves around the concept of linear dependence in the context of a matrix. The original poster presents a matrix and their attempts at row reduction, leading to questions about the implications of the results regarding linear dependence and the identification of non-trivial linear relations.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to determine linear dependence by analyzing the row-reduced form of the matrix and seeks to find a non-trivial linear relation. Participants question the recording of row operations and clarify the focus on either rows or columns in the context of linear combinations.

Discussion Status

The discussion is ongoing, with participants providing guidance on the relationship between row operations and linear combinations. There is an exploration of different interpretations regarding whether to consider rows or columns for the linear relations.

Contextual Notes

The original poster mentions multiple attempts to find the correct coefficients for the linear relation, indicating a struggle with the problem. There is also a reference to using a calculator for row reduction, which may influence the understanding of the problem.

mr_coffee
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Hello everyone, I'm finishing up some matrices review and im' confused on this question i have the matrix:
-1 -3 -1 2
5 13 3 -8
3 10 9 -8
1 4 7 -4

I row reduced got this:
1 0 0 3/5
0 1 0 -4/5
0 0 1 -1/5
0 0 0 0

So you can see that this isn't a basis due to column 5 not being 0 0 0 1, but what does this mean the questions says:
If they are linearly dependent, determine a non-trivial linear relation - (a non-trivial relation is three numbers which are not all three zero.) Otherwise, if the vectors are linearly independent, enter 0's for the coefficients, since that relationship always holds.
?A + ?B + ?C + ?D = 0.
I tried 1 1 1 3/5
1 1 1 0, i tried actually 14 times, all of them are wrong hah, any help?>
 
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Did you record the row operations that you used? Because they tell you the relationship, the reduced row of zeroes is a linear combination of the 4 rows, just recall what the combination is.
 
I used a Ti-83 calculator to find the row reduction, he said to use them for these problems!
 
You know how to solve a homogeneous system? If A is your matrix of column vectors, a non-trivial solution to the homogeneous system AX=0 will give you a non-trivial linear relation between your vectors.

AX is just a linear combination of the columns of A after all.

edit-are you concerned with a linear combination of the rows or the columns of your matrix? matt and i answered the different interpretations (in that order).
 
Last edited:

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