Answer
$a.\displaystyle \quad\frac{4}{5}$
$b.\displaystyle \quad\frac{8}{5}$
$c.\quad 3$
$d.\quad 0$
Work Step by Step
$ a.\quad$
$f(3, -1,2)=\displaystyle \frac{3-(-1)}{(-1)^{2}+(2)^{2}}=\frac{4}{5}$
$ b.\quad$
$f(1, \displaystyle \frac{1}{2}, -\frac{1}{4})=\frac{1-(\frac{1}{2})}{(\frac{1}{2})^{2}+(-\frac{1}{4})^{2}}=\frac{8}{5}$
$ c.\quad$
$f(0, -\displaystyle \frac{1}{3},0)=\frac{0-(-\frac{1}{3})}{(-\frac{1}{3})^{2}+(0)^{2}}=3$
$ d.\quad$
$f(2,2,100)=\displaystyle \frac{2-(2)}{(2)^{2}+(100)^{2}}=0$
