The slope of the line MN where M (9,6) and N (1,4) can be obtained by obtaining the rate of the rise over the run. This is shown below:
(y2 - y1)/(x2 - x1) = (4 - 6)/(1 - 9) = (-2)/(-8)
m1 = 1/4
The slope of the line perpendicular to line MN can be obtained by taking the negative reciprocal of the slope of line MN.
m1 = 1/4
m2 = -1/m1 = -1/(1/4) = -4
Therefore, the slope of the line perpendicular to line MN is -4.
