First you click on y=
Here you fill in:
y1= 2^x
y2= 8
After that you click on second - trace (also known as calc)
This gives you a few options. You pick the fifth which will be intersect.
After that you follow the instructions the calculator gives you.
Those instructions will be: give a point near the intersection on the first graph, give a point near the intersection on the second graph, and a guess. This guess can be anything near the intersection.
Now your calculator will give you the coordinates of the intersection
