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Mathematics 8 Online
OpenStudy (anonymous):

Can someone check this integral for me?

OpenStudy (anonymous):

wolframalpha.com

OpenStudy (cgreenwade2000):

oh stop it @jk_16

OpenStudy (anonymous):

stop it what..wolfram works

OpenStudy (cgreenwade2000):

The asker is probably looking for a way to learn it instead of a flat out answer.

OpenStudy (anonymous):

This^

OpenStudy (anonymous):

^

OpenStudy (anonymous):

lol kids..wolfram does just fine with the work..if u dont understand a part the solution, this is what we are here for

OpenStudy (cgreenwade2000):

lol @ kids who use wolfram

OpenStudy (anonymous):

\[\int\limits_{}^{}\csc^3x\]using Integration by parts u=cscx dv=csc^2x du=-cscxcotx v=-cotx \[-cscxcotx-\int\limits_{}^{}cscxcot^2xdx\] and then substitution with w=cotx dw=cscxcotxdx \[-cscxcotx-\int\limits_{}^{}-w dw = -cscxcotx+1/2 w^2 + c\]and a final answer of \[\int\limits_{}^{}\csc^3x = -cscxcotx+1/2\cot^2x+c\]

OpenStudy (anonymous):

Should be - (1/2)cot x csc x + (1/2) ln | csc x - cot x | + C

OpenStudy (cgreenwade2000):

If w = cotx then dw = -csc^2

OpenStudy (anonymous):

I think...

OpenStudy (anonymous):

@cgreenwade2000 It's csc^3(x)

OpenStudy (cgreenwade2000):

@Dido525 Right the remaining integral would be csc^3

OpenStudy (anonymous):

do u know what the reduction formula for integral csc^m(x) dx is

OpenStudy (anonymous):

Dido your answer above is the one in the back of the book, where did I go wrong from getting that answer?

OpenStudy (anonymous):

Hint: Use a trig identity for csc^2(x) when you intergrate by parts.

OpenStudy (anonymous):

Rewrite as ∫ csc²x csc x dx

OpenStudy (anonymous):

Now try again?

OpenStudy (anonymous):

csc²x dx = dv - cot x = v csc x = u - cot x csc x dx = du

OpenStudy (cgreenwade2000):

Can we stop this whole thing and have him rewrite the problem by fixing his second substitution?

OpenStudy (anonymous):

Okay.

OpenStudy (anonymous):

So that second substitution is bogus seeing as I somehow decided the derivative of cot was csccot. Anyways, without that substitution I am still stuck on where to go from\[-cscxcotx-\int\limits_{}^{}cscxcot^2(x)\]Any suggestions?

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