Answer
The slope is undefined.
Work Step by Step
We can use the slope formula to calculate the slope of a line, m, that goes through two points.
$m=\frac{y_{2}-y_{1}}{x_{2}-x_{1}}$
$m=\frac{-5-1}{-1-(-1)}=\frac{-(5+1)}{-1+1}=-\frac{6}{0}$
Any number divided by 0 is undefined, so the slope is undefined.