Chapter 8.1, Problem 19E

To determine

The vectors $X_1=\left(\begin{array}{c}1\\ -2\\ 4\end{array}\right)+t\left(\begin{array}{c}1\\ 2\\ 2\end{array}\right),X_2=\left(\begin{array}{c}1\\ -2\\ 4\end{array}\right),X_3=\left(\begin{array}{c}3\\ -6\\ 12\end{array}\right)+t\left(\begin{array}{c}2\\ 4\\ 4\end{array}\right)$ form a fundamental set on the interval $\left(-\infty ,\infty \right)$ or not.