Answer
A set of vectors {v1,v2,....,v5} in R4 is linearly independent when dim Span {v1,v2,.....,v5} = 4.
Work Step by Step
Since dim Span {v1,v2,.....,v5} is 4, matrix {v1,v2,....,v5} has four pivot columns. That means one column can be represented as a linear combination of others. So the set is linearly independent.
