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# C3 intergration by substitution help watch

1. How would you intergrate (x+2)/(2x-3)^3 dx
If u=2x-3
2. (Original post by toonervoustotalk)
How would you intergrate (x+2)/(2x+3)^3 dx
If u=2x-3
Strange substitution choice. Is it not u = 2x+3?

Anyway, what have you tried so far?
3. (Original post by SeanFM)
Strange substitution choice. Is it not u = 2x+3?

Anyway, what have you tried so far?
Because i made a mistake in the denominator
4. (Original post by toonervoustotalk)
Because i made a mistake in the denominator
What is the mistake?

And what working have you got so far for the question?
5. (Original post by toonervoustotalk)
How would you intergrate (x+2)/(2x+3)^3 dx
If u=2x-3
I think you meant u=2x+3.
Differentiate 2x+3 with respect to x and replace dx with 0.5du

then replace x+2 with some multiple of u (hint)

You should be able to integrate from there...
6. (Original post by toonervoustotalk)
You've replaced dx by du but forgot the /2.

The 1/2 from (u+3)/2 has also disappeared in your substitution.
7. (Original post by SeanFM)
You've replaced dx by du but forgot the /2.

The 1/2 from (u+3)/2 has also disappeared in your substitution.
I figured out after i sent it

This any better?
I know i somehow have to get ln something as 1/x intergrates to lnx
8. (Original post by toonervoustotalk)
I figured out after i sent it

This any better?
I know i somehow have to get ln something as 1/x intergrates to lnx
don't forget the du on the RHS. Re-arrange the fraction and integrate. You can take constants outside the integral if you want.

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