Originally Posted by
Jhevon since this is to be handed in, we can't give you a full solution. instead, try to see if you can get by on hints.
you want to find $\displaystyle 1700 \int_0^\infty te^{-0.5t}~dt = 1700 \lim_{N \to \infty} \int_0^N te^{-0.5t}~dt$
now, the standard way to approach this integral is to use integration by parts. using $\displaystyle u = t$ and $\displaystyle dv = e^{-0.5t}$
or, as an alternative, you could find $\displaystyle \frac d{dt} -te^{-0.5t} = \cdots$
integrate both sides and solve for the required integral