My book demonstrates how to test whether a set of vectors S = <mo fence="false" stretchy="

Aiden Barry

Aiden Barry

Answered question

2022-05-23

My book demonstrates how to test whether a set of vectors S = { v 1 , v 2 , v 3 } is linearly independent by writing c 1 v 1 + c 2 v 2 + c 3 v 3 = 0, equating corresponding components to form a system of linear equations, and then reducing the augmented matrix of this system using Gauss-Jordan elimination.
My question is, couldn't you just evaluate the determinant of the matrix rather than using elimination? Couldn't you say that if the determinant is nonzero, the system has only the trivial solution and therefore S is independent; and if it's zero, the system has infinitely many solutions (since we know it can't have no solutions as it has at least the trivial solution) and S is therefore dependent? Or do you have to use Gaussian elimination?

Answer & Explanation

thoumToofwj

thoumToofwj

Beginner2022-05-24Added 16 answers

Determinant is defined only for square matrices. So the answer to your question depends on what vector space are the vectors v 1 , v 2 , v 3 in.
For instance, if v 1 = v 2 = v 3 = ( 1 , 1 ) T , what matrix do you get?
By the way, S is a set, not a matrix. One gets a matrix by making the columns as v 1 , v 2 and v 3 .

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