Question 80719
The slope of a line passing through two points (x1, y1) and (x2, y2) is given by:
{{{m = (y[2]-y[1])/(x[2]-x[1])}}}
In this problem:
{{{m = (-1-(-1))/(-2-(-9))}}}
{{{m = (-1+1)/(-2+9)}}}
{{{m = 0/7}}}
{{{m = 0}}}
The slope is 0 which means the line is horizontal.