Question 47733
f(x) = 1 - 2^-x
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You start with y=2^x which is an increasing exponential function.
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You have two negatives to consider.
The -x reflects the curve in the y-axis so it looks like a 
decreasing exponential function.
The - in front of the 2^-x  reflects it in the x-axis.
The 1 moves it up one unit.
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Cheers,
Stan H.