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Mertsj
 4 years ago
Integral Question Using integration by parts
Mertsj
 4 years ago
Integral Question Using integration by parts

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Mertsj
 4 years ago
Best ResponseYou've already chosen the best response.5\[\int\limits_{?}^{?}e ^{2\theta}\sin 3\theta d \theta\]

myininaya
 4 years ago
Best ResponseYou've already chosen the best response.6e^(2x) sin(3x) 2e^(2x) 1/3*cos(3x) 4e^(2x) 1/9*sin(3x) ..... \[=e^{2x} \cdot \frac{1}{3} \cos(3x)\int\limits_{}^{}2 e^{2x} \cdot \frac{1}{3}\cos(3x) dx\] \[=e^{2x} \cdot \frac{1}{3} \cos(3x)[2 e^{2x} \cdot \frac{1}{9} \sin(3x)\int\limits_{}^{} 4 e^{2x} \cdot \frac{1}{9} \sin(3x) dx]\] So we have \[\int\limits_{}^{}e^{2x} \sin(3x) dx=\frac{e^{2x}}{3} \cos(3x)+\frac{2e^{2x}}{9} \sin(3x)\frac{4}{9}\int\limits_{}^{}e^{2x} \sin(3x) dx\]

myininaya
 4 years ago
Best ResponseYou've already chosen the best response.6Solve for \[\int e^{2x} \sin(3x) dx\]

myininaya
 4 years ago
Best ResponseYou've already chosen the best response.6\[\frac{13}{9} \int\limits_{}^{}e^{2x} \sin(3x) dx=\frac{e^{2x}}{3} \cos(3x)+\frac{2e^{2x}}{9} \sin(3x) +C\]

myininaya
 4 years ago
Best ResponseYou've already chosen the best response.6You might want to check me for airthmetic errors.

Mertsj
 4 years ago
Best ResponseYou've already chosen the best response.5Thank you very much, my dear. I did have the correct f and g' identified and got to the point where you said "and so we have" but I couldn't identify that as progress. Thanks again.

myininaya
 4 years ago
Best ResponseYou've already chosen the best response.6Np. :) I hope I put enough details as far as me showing my work. Let me know if you don't understand one of the steps.

Mertsj
 4 years ago
Best ResponseYou've already chosen the best response.5I will. Hopefully I can figure out the algebra.

Mertsj
 4 years ago
Best ResponseYou've already chosen the best response.5When we have: \[\int\limits_{?}^{?}2e ^{2x}(\frac{1}{3}\cos (3x)dx)\] Why don't we just pull out the constant 2/3?

myininaya
 4 years ago
Best ResponseYou've already chosen the best response.6i was just showing how you can use a table

Mertsj
 4 years ago
Best ResponseYou've already chosen the best response.5Perfect!! I got it. \[\frac{1}{13}e ^{2x}(2\sin 3x3\cos 3x)\]

Mertsj
 4 years ago
Best ResponseYou've already chosen the best response.5Yep. I never would have thought of that trick of solving for the integral after it appeared again.

myininaya
 4 years ago
Best ResponseYou've already chosen the best response.6That is a nice little trick that comes in handy with these trig guys!

Mertsj
 4 years ago
Best ResponseYou've already chosen the best response.5Yes. I think I knew it 50 years ago but didn't remember it now.

myininaya
 4 years ago
Best ResponseYou've already chosen the best response.6You sound as old as amistre. hehe
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