Problem:
Using the TI-85 graphing calculator, graphically determine which of the
following functions
y = x7 and y = 4x
has larger values for x large.
Visualization:

[Press here to see animation again!]
- If you are not familiar with the graphing of functions on the TI-85,
then first read the
Initial Setup
page from
Little's Basic Guide to the TI-85.
- Press the GRAPH key and then pick y(x)=
by pressing the F1 key.
- If necessary, keep pressing the F4 key until only
y1= appears on the screen.
- At the prompt y1=, type in
x^7
and press the ENTER key.
- At the prompt y2=, type in
4^x
and press the ENTER key.
- The range settings for the graph above is  [0, 10] × [0, 106]:

- Pick GRAPH from the menu by pressing the F5.
Since y = x7 was entered first, it is graphed first:

followed by the graph of y = 4x:

- It appears that the function y = x7 has larger values.
- However, this does not continue to happen for x larger.
Choose range settings  [10, 15] × [0, 5 × 108]; the graph of y = x7 is

and is followed by the graph of y = 4x:

- Now it appears that the function y = 4x has larger
values. This, in fact, can be verified by using l'Hospital's Rule.
Alternative methods for doing this type of exploration:
- Consider the graph of x7 - 4x:

with viewing window [0, 50] × [-10, 10].
- Consider the graph of x7 / 4x:

with viewing window [0, 50] × [0, 2].