Possibilities:
We will perform Gaussian elimination (row reduction) on the vectors as rows to figure out what space is spanned:
The space spanned is
To answer both parts of the question at once, it is more convenient to perform Gaussian elimination on the system of equations for c1, c2, and c3:
This has the vectors as columns.
Forward elimination:
Back substitution:
From (2), c2=-c3; from (1), c1=-2c3.
Since c1, c2, and c3 need not be zero, the vectors are linearly dependent.
Taking c3=-1 gives c1=2 and c2=1, hence