Integral Help: int [0 to pi] [e^3t sin 3t] dt

[my_jam2]

\Pi
/ e^3t (sin 3t) dt = ?
\0


I get e^3t * -.307


What am I missing or doing wrong :?: [/img]

 

[tkhunny]

For starters, why do you still have a 't'? That should go away.

Have you noticed that your argument is negative in roughly (1,2)? This could give you difficult results.

What methods are you using to find the antiderivative?

 

[stapel]

\Pi
/ e^3t (sin 3t) dt = ?
\0

Do you mean "e^3t sin(3t)", "e³ t sin(3t)", "e^3t sin³(t)", or something else?

I get e^3t * -.307

How? Please reply with all of your steps.

Thank you.

Eliz.

 

[galactus]

Try integration by parts.

\(\displaystyle \L\\\int{udv}=uv-\int{vdu}\)

I will assume you mean \(\displaystyle e^{3t}sin(3t)\)

\(\displaystyle \text{Let}\L\\u=e^{3t}\\dv=sin(3t)dt\\du=3e^{3t}\\v=\frac{-cos(3t)}{3}\)

 

[my_jam2]

Integer upper limit = pi
(e)exp(3t) sin (3t) dt = ?
Integer lower limit = 0


I hope that this will clear up the problem for you.


I used the integer formula: (e)exp(au) sin bu du = (e)exp(au)*(asinbu-bcosbu)
-------------------------------
a^2 + b^2

exp:means exponent

symbol ^:indicates exp

 

[my_jam2]

Integer upper limit = pi
(e)exp(3t) sin (3t) dt = ?
Integer lower limit = 0


I hope that this will clear up the problem for you.


I used the integer formula: (e)exp(au) sin bu du =
[(e)exp(au)*(asinbu-bcosbu)]
-------------------------------
a^2 + b^2

exp:means exponent

symbol ^:indicates exp

 

[pka]

Is this you problem \(\displaystyle \L
\int_0^\pi {e^{3t} \sin (3t)dt}\)?

I realize you probably do not know this, but exp(3x) means \(\displaystyle \L
{e^{3t} }\) to any mathematician.

You ought to learn to use LaTeX for posting these types of question.

 

[my_jam2]

pka reply

That is the problem in proper notation.

What is LaTeX and where can I get it ?

 

[galactus]

Click on the 'quote' at the upper right corner of pka's post. You can see the code used there.

 

[tkhunny]

Integer upper limit = pi
Integer lower limit = 0
I used the integer formula

I'm guessing you mean "integral"?