@hartnn

Question

@hartnn

hartnn · Answer

Hi Lui :)

luigi0210 · Answer

Yes I still need help please >.< Last one closed.. http://prntscr.com/3ekqa9 But you sure a u-sub would work?

hartnn · Answer

yes! 
whenever there is a linear expression within $\large \sqrt[n]{linear}$
we substitute u = linear expression

hartnn · Answer

after the substitution, you just need to separate the denominator :)

hartnn · Answer

did you try it ?

luigi0210 · Answer

OS is still lagging for me, sorry. And I have never done a problem like this before so I don't really follow :/

hartnn · Answer

ok, never substituted in an integral ??

we need to replace every 'x' by a 'u'
so wherever you see x, replace it by 'u-9'

also, find du

hartnn · Answer

u = x+9

thats why x = u-9

and du =...?

luigi0210 · Answer

I've done sub before.. 
$u=x+9$ and $du=dx$ 
Leaving us with $\Large \int \frac{x}{\sqrt{u}} du$?

hartnn · Answer

not actually, as i said, we need to replace EVERY 'x' by a u
after there substitution, there should not by any 'x' left.

luigi0210 · Answer

OH, now I see what you mean! 
$\Large \int \frac{u-9}{\sqrt[4]{u}} du$?

luigi0210 · Answer

OS is switching the replies .-.

hartnn · Answer

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