Let x be a continuous variable defined over the interval $$\left( { - \infty ,\,\infty } \right)$$  , and f(x) = e<sup>-x-e<sup>-x</sup></sup> . The integral $${\text{g}}\left( {\text{x}} \right) = \int {{\text{f}}\left( {\text{x}} \right){\text{dx}}} $$    is equal to

Correct Answer: e<sup>-e<sup>-x</sup></sup>