Uh oh! Wolfram|Alpha doesn't run without JavaScript.
Please enable JavaScript. If you don't know how, you can find instructions
here
.
Once you've done that, refresh this page to start using Wolfram|Alpha.
solve(derivate(-(6.8*^9 (e^(21-0.6 t)-0.6 e^(21-0.6 t) (t+2)))/(e^(21-0.6 t) (t+2)+1)^2)=0,t)
Natural Language
Math Input
Extended Keyboard
Examples
Upload
Random