Solution SS.C43 Robert Beezer
Form a linear combination, with unknown scalars, of $R$ that equals $\vect{z}$, \begin{equation*} a_1\colvector{2\\-1\\3\\4\\0}+ a_2\colvector{1\\1\\2\\2\\-1}+ a_3\colvector{3\\-1\\0\\3\\-2} = \colvector{1\\1\\5\\3\\1} \end{equation*} We want to know if there are values for the scalars that make the vector equation true since that is the definition of membership in $\spn{R}$. By Theorem SLSLC any such values will also be solutions to the linear system represented by the augmented matrix, \begin{equation*} \begin{bmatrix} 2 & 1 & 3 & 1\\ -1 & 1 & -1 & 1\\ 3 & 2 & 0 & 5\\ 4 & 2 & 3 & 3\\ 0 & -1 & -2 & 1 \end{bmatrix} \end{equation*} Row-reducing the matrix yields, \begin{equation*} \begin{bmatrix} \leading{1} & 0 & 0 & 0\\ 0 & \leading{1} & 0 & 0\\ 0 & 0 & \leading{1} & 0\\ 0 & 0 & 0 & \leading{1}\\ 0 & 0 & 0 & 0 \end{bmatrix} \end{equation*} With a pivot column in the last column, the system is inconsistent (Theorem RCLS), so there are no scalars $a_1,\,a_2,\,a_3$ that will create a linear combination of the vectors in $R$ that equal $\vect{z}$. So $\vect{z}\not\in R$.