Question 1068162
The asymptote is not relevant to her account, since she didn't start from 0 money, compoundings are not negative. The asymptote exists for the function itself, but negative values of x are not relevant.
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50000(1.15)^4=$87,450
Now using 4% for t years
N(t)=87450(1.04)^t
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This is a little ambiguous, because it is implied in the new function that x cannot be negative, so there is no asymptote.  It is a piecewise function, made up of the first and the second, which are different curves.  
Mathematically, however, the new function has an asymptote of 0 as well, since with infinitely large negative x, the function becomes 0.