$$\color{rgb(0,0,255)}\vec{u}$$

$$\color{rgb(127,0,0)}k\vec{u}$$

$$\color{rgb(0,0,0)}k =$$

$$\color{rgb(0,0,0)}= -\frac{1}{2}$$

$$\color{rgb(0,0,255)}\vec{u}\left( \begin{array}{l} {2 } \\ {- 3 } \end{array} \right)$$

$$\color{rgb(127,0,0)}k\vec{u}\left( \begin{array}{l} {-\frac{1}{2}\times 2 } \\ {-\frac{1}{2}\times \left( - 3 \right) } \end{array} \right)$$

$$\color{rgb(127,0,0)}k\vec{u}\left( \begin{array}{l} {- 1 } \\ {1.5 } \end{array} \right)$$