Column vectors are written as rows, such as $\mathbf{x}=\left(x_{1}, x_{2}\right),$ and $T(\mathbf{x})$ is written as $T\left(x_{1}, x_{2}\right)$.
Show that the transformation $T$ defined by $T\left(x_{1}, x_{2}\right)=$ $\left(2 x_{1}-3 x_{2}, x_{1}+4,5 x_{2}\right)$ is not linear.