. This is because any vertical line has a x or "run" of zero. Whenever zero is the denominator of the fraction in this case of the fraction representing the slope of a line, the fraction is...
To find the slope you need to find the Y-Intercept (the line that crosses through the Y-Axis) then on the Y-Intercept move one unit to the right and go either up or down until you've hit the diagonal...
The formula for finding a line when the slope and y-intercept are known is as follows:
y = mx+b
m is the slope
b is the Y-intercept
Just substitute the slope for m and the Y-intercept for b.
An equation of a line can be put into the form: y = mx + b, where m is the slope and b is the y-intercept. So if the slope is -2 the equation should be able to be rearranged into y = -2 + b, and the...