It is not possible to have an -intercept = -1, nor is -intercept = -2 possible either.

Intercepts are points, and points, in , are designated by ordered pairs.

Now, if the -intercept is the point  and the -intercept is the point , the slope can be determined using the slope formula:

 where  and  are two given points on the line in question.

I would hope that the designation of the -intercept would be obvious.