I was given a question, i am to use determinants to find out if the following 3 vectors are linearly independent. The following x's are columns but im not sure how to type out columns so they are posted as rows.

x1=7,1,5,6

x2=5,2,4,1

x3=2,-1,1,1

To use determinants you need a square matrix correct? and to do that i simply added a 4th column of 0,0,0,0. This would make the determinant 0 and mean the matrix is linearly independent? This seems way to easy, as if im overlooking something.