mathematics
posted by trina .
Draw a graph of the mirror line y=x, the function f:x 3x+2 and its inverse f`1 x x2/3, for the domain of x, 2<x<8
x 2 0 4 8
y=x 2 0 4 8
These numbers were given to me what i want to know is why 0 and 4 and how do i come up with the numbers on my own for future questions??

The choice of x vales to use depends very much on the question and what you are asked to show. It is quite usual to calculate the value for x=0. In this case where the function is a straight line you only really need to have values for x=2 and x=8 and then draw the straight line between them.
Where the function is not a straight line then having several values helps to construct the line. It is usual to have both +ve and  values of x. 
The question requires you to graph the three functions. The xvalues given are suggested values, as explained by Dr. Russ.
Plot the functions graphically and you will be able to make observations and remarks.
Here's my version of the graph:
http://i263.photobucket.com/albums/ii157/mathmate/trina.png