Ugh. I don't even remember if this was in Calc I or II.
Anyway, I'm integrating exp(-Dt)dt. If I set u=exp(-D), v=exp(t), I get exp(-Dt). If I set u=1, x=exp(-Dt), I get -1/D*exp(-Dt). Those are not the same. Why aren't they the same?
ceresWhen the last moon is cast over the last star of morningAnd the future has past without even a last desperate warningRegistered User, Moderatormod
edited December 2009
It's Calc I. I have it now. The final is next week. Please kill me.
ceres on
And it seems like all is dying, and would leave the world to mourn
Ugh. I don't even remember if this was in Calc I or II.
Anyway, I'm integrating exp(-Dt)dt. If I set u=exp(-D), v=exp(t), I get exp(-Dt). If I set u=1, x=exp(-Dt), I get -1/D*exp(-Dt). Those are not the same. Why aren't they the same?
The product of exp(-D) and exp(t) is exp(-D + t).
EDIT: Oops, eeccccoo beat me to it. Guess I should actually read the other replies before making my own :P
Posts
also, this might help
why are you integrating by parts?
u = exp(-D)
v = exp(t)
Then
uv = exp(-D) * exp(t) = exp(-D + t) =/= exp(-Dt)
?
The product of exp(-D) and exp(t) is exp(-D + t).
EDIT: Oops, eeccccoo beat me to it. Guess I should actually read the other replies before making my own :P
Nah, don't fuss.
You're not the first person to have made this mistake.
Besides, now that you've made the mistake publicly, you'll remember when it comes to your exam!