Question 175967
SLOPE=(Y2-Y1)/(X2-X1)
SLOPE=(2-2)/(2+4)=0/6=0 
THUS THIS LINE IS A HORIZONTAL LINE PASSING THROUGH Y=2.
{{{ graph( 300, 200, -6, 5, -10, 10, y = 2) }}} (graph 300x200 pixels, x from -6 to 5, y from -10 to 10, y = 2).