Graphing a exponential problem

[crm08]

Homework Statement

The problem asks to graph tangent lines to the given function y = (ln(x)/x, and gives the points (1,0) and (e, 1/e)

Homework Equations

The Attempt at a Solution

I got the answer by taking the derivative and finding the slope, and at the point (e,1/e) the equation of the tangent line is y = 1/e, but it also asks to graph the problem and using a ti-89, the only exponential button is e^(x), which requires a "x" value. Any suggestions on how to enter this tangent line on my calculator, I tried y = 1/((1+x)^(1/x)) because the denominator is the definition of "e", but it showed up as a bunch of random lines

 

[The Dagda]

Can you not just use $e^1$ and $\frac{1}{e^1}\equiv{e^{-1}}$ which is e and 1/e?