Re: intercepts
If you have an equation in x and y and you graph that equation it may or may not cross one or both of the axes. In fact it may or may not cross the axes more than once.
Now, if it crosses the x-axis at one or more points, each point will have a y value of 0. For instance the points (-3,0), (2,0) and (513.12,0) are all points on the x-axis. So, given an equation, to find the points of the equation that are on the x-axis, set y in the equation equal to 0. Then solve the resulting equation for x. That will produce all the x-values of the point(s) of the equation that are on the x-axis.
A similar process is used to find the y-intercepts.
