Answer
The vectors $\vec{u}$ and $\vec{v}$ are not perpendicular.
Work Step by Step
$\vec{u}=4\vec{i}$ $,$ $\vec{v}=-\vec{i}+3\vec{j}$
Find $\vec{u}\cdot\vec{v}$ by multiplying corresponding components and adding"
$\vec{u}\cdot\vec{v}=(4)(-1)+(0)(3)=-4+0=-4$
Since the dot product of these two vectors is not equal to $0$, they are not perpendicular.
