#### Answer

$(y-2)^2=-8(x-3)$

#### Work Step by Step

We are given that the focus is to the left of the given vertex, thus, $ p$ is the negative of the distance between the two points.
So, $p=-|3-1|=-2$
Since the vertex and focus have the same y-coordinate, the parabola must have a horizontal axis.
Now, we will write the equation for the parabola that has a horizontal axis using the vertex and p.
$(y-k)^2=4p(x-h)$
$\implies (y-2)^2=-8(x-3)$