Thread: Generic Calculus Questions

An electron moving along the x axis has a position given by x = 12te^(-2.1 t) m, where t is in seconds. How far is the electron from the origin when it momentarily stops?



The answer is 2.102m, but I only know that because I understand that I need to find the derivative of x = 0 for t (x's slope will be 0 when it 'stops moving'). Time t will give me the position in the original equation. The actual values I got only because I know a thing or two about getting around my calculator, but I want to know how to take the derivative of the original equation on paper. Can anyone show me how to do this?


[EDIT]: dx/dt = (12 - 25.2t)e^(-2.1t) is that correct? If so, then my next problem involves getting t onto one side of the equation so that I can solve for it.