how do I find the integral of te^-3t dt? I started by setting u=t and dv or v'=e^-3t but don't seem to come out with the right answer. Help appreciated!

Question

myininaya · Answer

your setup looks good
and you are doing integration by parts i assume

myininaya · Answer

So then you would write
uv-int(u'v)dx

kl0723 · Answer

yes, integrations by parts and I come out with du = dt and v = -3e^-3t... not sure if that's right for the v value

myininaya · Answer

that v is where you went wrong

aum · Answer

v = -1/3 * e^(-3t)

myininaya · Answer

constant multiple should be -1/3 not -3

myininaya · Answer

Like you found the derivative instead of integrating

kl0723 · Answer

Thank you! I was not aware of that... already solved :)

myininaya · Answer

congrats

anonymous · Answer

$$I=\int\limits t e ^{-t}dt=t \frac{ e ^{-t} }{ -1 }-\int\limits 1*\frac{ e ^{-t} }{ -1 }dt=-t e ^{-t}+\frac{ e ^{-t} }{ -1 }+c$$