#Integration by parts DI method

31 messages · Page 1 of 1 (latest)

slim skiff
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Differentiate x, integrate e^x.

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I feel like you could've figured that out yourself.

royal dawn
unique summitBOT
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kangaroo rat

slim skiff
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...do you mean xe^(5x)?

royal dawn
slim skiff
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Okay... same answer.

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And I don't see how that's any harder to figure out.

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If one of the two functions goes to 0 when you differentiate it enough and the other function is one you know how to integrate at all, you always differentiate the function that goes to 0.

royal dawn
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oh

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thanks

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/close

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@slim skiff When you integrate e^5x it is 1\5 e^5x You need integration by parts for that and a video I watched said if you need to use integration by parts for integration by parts don't integrate what you were integrating to get integration by parts. What do I do?

slim skiff
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Why do you think you would need integration by parts? Integration by parts is for a product of functions.

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Not a composition of functions.

royal dawn
royal dawn
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because there is two terms...

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im wrong probably.

slim skiff
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Okay, let's do an experiment. Integrate (1/5)e^(5x) by parts, differentiating 1/5.

slim skiff
royal dawn
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yes

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the integral of e^5x is exactly what the question was

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what does it mean when the bot reacts to me...

slim skiff
royal dawn
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oh

slim skiff
# royal dawn the integral of e^5x is exactly what the question was

I meant, "notice how the derivative of 1/5 is 0?" So the integral of (1/5)e^(5x) is just 1/5 times the integral of e^(5x). Demonstrating that constant multiples don't factor into integrals. In fact, it's common practice to factor constant multiples all the way out to the left of the integral symbol.

royal dawn
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oh

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thanjs