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Mathematics 15 Online
OpenStudy (itiaax):

Integration by substitution help. *question below*

OpenStudy (itiaax):

Can I have some help on this question, please?

geerky42 (geerky42):

@jim_thompson5910 @zepdrix @ikram002p They can help.

zepdrix (zepdrix):

Oh you again! :x the panda lady!

zepdrix (zepdrix):

\[\Large\rm \int\limits \frac{1}{1+\sqrt x}(dx)\] Hmm let's try using the substitution that they suggest, and see what happens.

zepdrix (zepdrix):

\[\Large\rm u=1+\sqrt x\]\[\Large\rm du=\frac{1}{2\sqrt x}dx\qquad\to\qquad 2\sqrt x~du=dx\]

zepdrix (zepdrix):

In the differential equation.. thing... we need that sqrt(x) in terms of u. So we'll go back to our original substitution and solve for sqrt(x).

zepdrix (zepdrix):

\[\Large\rm u=1+\sqrt x\qquad\to\qquad u-1=\sqrt x\]

zepdrix (zepdrix):

\[\Large\rm 2\sqrt x~du=dx\qquad\to\qquad 2(u-1)du=dx\]

zepdrix (zepdrix):

Ya? How bout that? :O That's pretty fancy, huh?

OpenStudy (itiaax):

@zepdrix haa, let me process it ^_^

OpenStudy (itiaax):

I get that bit :D

zepdrix (zepdrix):

So then plug in your goodies,\[\Large\rm \int\limits\limits \frac{1}{1+\sqrt x}[dx]\quad=\quad \int\limits \frac{1}{u}\left[2(u-1)du\right]\]

zepdrix (zepdrix):

And it shouldn't be too bad from there :O What do you think? Remember how to split up fractions and stuff?

OpenStudy (itiaax):

Hmm, split up fractions? :o

OpenStudy (itiaax):

I'm lost :s

zepdrix (zepdrix):

\[\Large\rm =2\int\limits \frac{u-1}{u}du\]

zepdrix (zepdrix):

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