Position of Electron Moving Along x-Axis at Momentary Stop

[jjc39]

A electron moving along the x-axis has a position given by x = 18 te-2.5 t m, where t is in seconds. How far is the electron from the origin when it momentarily stops?

I am pretty sure that I have to differentiate this equation, and find where it equals zero and solve, I guess the biggest problem that I am having is doing the differentiating, some help please.

 

[Astronuc]

Is the equation x(t) = 18t e^-2.5t?

Can one differentiate f(t)*g(t) and exponentials? Here f(t) = 18t and g(t) = e^-2.5t