But "e"isa number! It's the natural exponential and the base of the natural logarithm, and is approximately equal to 2.7.

This was supposed to have been covered in class before assigning work on it. To study this on your own, trysome online lessons.

Note: If you look on your calculator and find the button marked "LN" (or "ln"), the "2nd" function should be something like "e^". Use this key to do the evaluation of 1 + e^(-3). The denominator should evaluate to approximately 1.049787.