We have been given a rational function:

And we are required to determine an appropriate viewing rectangle for the graphing calculator.
An appropriate viewing rectangle is the set of minimum and maximum values of x and y on which all important attributes of the graph are clearly displayed.
For the given function, an appropriate viewing rectangle will be [-20,20,2] by [-20,20,2].
This function, when graphed using a graphing calculator on the said viewing rectangle, it appears as attached.