50 ! the exponential function f(x)=a^x,a> 0,a≠1 what is the domain? what is the range?

I have included a graph to help you see what the domain and range would be
There are no minus y values. 
0<y< infinity y is included in the reals.
The domain is 
- infinity < x < infinity.

I don't want to say that either x or y can equal - or + infinity. Some teachers allow it. You have to ask your instructor what they will accept.

The blue line is y = 4^x
The red line is y = 2^x  

450 + 285 + 325 = 1,060

this problem makes no sense.