Ask your own question, for FREE!
Calculus1 19 Online
OpenStudy (anonymous):

Can someone help me with the antiderivative of this function.

OpenStudy (anonymous):

\[\int\limits_{}^{}\frac{ x+1 }{ \sqrt{x} - 1 } \]

OpenStudy (anonymous):

@freckles @FibonacciChick666

OpenStudy (fibonaccichick666):

is it justthe squareroot of x on the bottom?

OpenStudy (anonymous):

Yes

OpenStudy (fibonaccichick666):

ok, I recommend multiplying by the conjugate to see if it gets you something nicer

OpenStudy (anonymous):

This is the answer. To be honest I don't even know how to approach this one.

OpenStudy (dan815):

oh wow lol

OpenStudy (anonymous):

yes lol

OpenStudy (anonymous):

\[\int\limits_{}^{}\frac{x+1}{\sqrt{x}-1}dx = \int\limits_{}^{}\frac{x}{\sqrt{x}-1}dx + \int\limits_{}^{}\frac{1}{\sqrt{x}-1}dx\] and then integrate by parts?

OpenStudy (dan815):

yah gives u right sndwer

OpenStudy (dan815):

x/sqrx-1 will take some work

OpenStudy (anonymous):

I lied; it's a substitution problem

OpenStudy (anonymous):

You split the integral into 2 like before For each integral, let:\[u = \sqrt(x)-1\] Which means \[du = \frac{1}{2\sqrt{x}}dx\] Which means\[dx = 2\sqrt{x} * du\]

OpenStudy (anonymous):

\(\frac{2 x^{3/2}}{3}+x+4 \sqrt{x}+4 \log \left(1-\sqrt{x}\right)\)

OpenStudy (fibonaccichick666):

is it easier if we make it look like this:\[\int \frac{(x+1)(\sqrt{x} +1)}{x-1}\]

OpenStudy (fibonaccichick666):

then we can use polynomial division to annihilate part of it

OpenStudy (anonymous):

\[dx = 2(u+1)du\]

OpenStudy (anonymous):

For the integrand \(\frac{x+1}{\sqrt{x}-1}\), substitute \(u=\sqrt{x}\) and \(du=\frac{1}{2 \sqrt{x}} \, dx\): \(= 2 \int \frac{u \left(u^2+1\right)}{u-1} \, du\) For the integrand \(\frac{u \left(u^2+1\right)}{u-1}\), do long division: \(= 2 \int \left(u^2+u+\frac{2}{u-1}+2\right) \, du\)

OpenStudy (anonymous):

Integrate the sum term by term and factor out constants: \(= 2 \int u^2 \, du+4 \int 1 \, du+4 \int \frac{1}{u-1} \, du+2 \int u \, du\)

OpenStudy (anonymous):

For the first integral, we substitute in and get: \[\int\limits_{}^{}\frac{(u+1)^2}{u}(2[u+1]du)\] which is equal to \[2\int\limits_{}^{}\frac{(u+1)^3}{u}du\] This integral should be straight forward

OpenStudy (anonymous):

This is a serious question. :/

OpenStudy (anonymous):

For the second integral susbstitution, we get \[\int\limits_{}^{}\frac{1}{u}*dx\] substitute the dx from before, and you should get another straightforward integral

OpenStudy (fibonaccichick666):

I like alchemista's substitution better

OpenStudy (anonymous):

I like it too

OpenStudy (anonymous):

Everyone deserves a medal for this one

Can't find your answer? Make a FREE account and ask your own questions, OR help others and earn volunteer hours!

Join our real-time social learning platform and learn together with your friends!
Can't find your answer? Make a FREE account and ask your own questions, OR help others and earn volunteer hours!

Join our real-time social learning platform and learn together with your friends!