Answer
See the explanation below.
Work Step by Step
${\bf u}=\langle u_{1}, u_{2}, u_{3}\rangle$ has magnitude $|{\bf u}|=\sqrt{u_{1}^{2}+u_{2}^{2}+u_{3}^{2}}$
and direction $\displaystyle \frac{1}{\sqrt{u_{1}^{2}+u_{2}^{2}+u_{3}^{2}}}\cdot\langle u_{1}, u_{2}, u_{3}\rangle$
Multiplying by a positive scalar,
$ c{\bf u}=c\langle u_{1}, u_{2}, u_{3}\rangle=\langle cu_{1}, cu_{2}, cu_{3}\rangle$
$c{\bf u} $ has the same direction as ${\bf u}$ and its magnitude changes by factor $c$.
If the scalar $c$ is zero, the vector $c{\bf u}$ is the zero vector, and has no direction, with magnitude of 0.
If the scalar is negative, the direction of $c{\bf u}$ is opposite to the direction of ${\bf u}$ and the magnitude changes by factor $|c|.$
