Answer
$d\approx 4.12
\text{ units}
$
Work Step by Step
Using $d=\sqrt{(x_1-x_2)^2+(y_1-y_2)^2}$ or the Distance Formula, then the distance, $d$, between the given points $(
3,5
)$ and $(
4,1
)$ is
\begin{array}{l}\require{cancel}
d=\sqrt{(3-4)^2+(5-1)^2}
\\\\
d=\sqrt{(-1)^2+(4)^2}
\\\\
d=\sqrt{1+16}
\\\\
d=\sqrt{17}
\\\\
d\approx 4.12
\text{ units}
.\end{array}