The area of the top surface of an 8.5 inch by 11 inch piece of paper is a function of the number of times it is folded in half.
what is the value of a and what does it represent in ab^x?
i don't understand how to write the equation.

This scenario produces a geometric sequence.  Meaning that there is a common ratio that is constant from term to term.  Each time that the paper is folded the top area is halved.  Thus the common ratio is one half...

The equation for a geometric sequence (and really very similar to any type of exponential function) is:

a(n)=ar^(n-1),  where a(n) is the value of the nth term, a=initial value, r=common ratio, and t=the term number...in this case, r=1/2 and a=8.5*11

a(n)=93.5(.5^(n-1))  

Specifically the question asked what a was in ab^x, a=initial area.

820,000 is the answr

Then just do it (lol)