## Differential Equations and Linear Algebra (4th Edition)

We know that for a matrix $\left[\begin{array}{rrr} a & b & c \\ d &e & f \\ g &h & i \\ \end{array} \right]$ the determinant, $D=a(ei-fh)-b(di-fg)+c(dh-eg).$ Hence here $D=1(6-(-1))-(-2)(4-4)+1(-2-12)=1(7)+2(0)+1(-14)=7-0-14=-7\ne0$, thus they are not coplanar, thus they span the space.