Simplifying an expression with exponents

[tmt1]

I have this expression

$$\frac {1} { e^x + \frac {1} {e^x}}$$

and it simplifies to

$$\frac {e^x} { e^{2x} + 1}$$

And I'm not sure how to get this simplification or what rules to apply to get to this simplification.

 

[MarkFL]

Multiply your original expression by:

$$1=\frac{e^x}{e^x}$$