


This Question is Closed

Asylum15
Best Response
You've already chosen the best response.
0
\[\int\limits \frac{ lnx }{ x }\]

Asylum15
Best Response
You've already chosen the best response.
0
Whos feelin brave? :D

TuringTest
Best Response
You've already chosen the best response.
0
I'm thinking by parts...

surdawi
Best Response
You've already chosen the best response.
0
u du

Siddharth18
Best Response
You've already chosen the best response.
0
do it by substitution, let lnx= u

TuringTest
Best Response
You've already chosen the best response.
0
haha, oh yeah, I overthought it :P

Asylum15
Best Response
You've already chosen the best response.
0
Can U be lnx ? It's above the line

TuringTest
Best Response
You've already chosen the best response.
0
so?

surdawi
Best Response
You've already chosen the best response.
0
dw:1353166961045:dw

Siddharth18
Best Response
You've already chosen the best response.
0
dw:1353035523772:dw

waterineyes
Best Response
You've already chosen the best response.
2
Put ln(x) = u
So: \(\frac{1}{x} \cdot dx =du\)

Asylum15
Best Response
You've already chosen the best response.
0
Thank you guys

waterineyes
Best Response
You've already chosen the best response.
2
Just try and if you face any problem, then do ask us...

Asylum15
Best Response
You've already chosen the best response.
0
Wait, can you expand on that for me?
I have \[dx = \frac{ du }{ 1/x }\]

waterineyes
Best Response
You've already chosen the best response.
2
Are you converting a simple solution to hard one??

Asylum15
Best Response
You've already chosen the best response.
0
Looks like it xD

waterineyes
Best Response
You've already chosen the best response.
2
dw:1353167337486:dw

waterineyes
Best Response
You've already chosen the best response.
2
Sorry, my handwriting is not too good..

Asylum15
Best Response
You've already chosen the best response.
0
Is this a direct manipulation or a substitution?

waterineyes
Best Response
You've already chosen the best response.
2
Is this not Substitution ??
We are substituting u in place of x..

Asylum15
Best Response
You've already chosen the best response.
0
Ah, ok, so lnx. Differentiation of ln = 1 over
So 1/x right?

waterineyes
Best Response
You've already chosen the best response.
2
Yes..

waterineyes
Best Response
You've already chosen the best response.
2
\[\frac{d}{dx}\ln(x) = \frac{1}{x}\]

Asylum15
Best Response
You've already chosen the best response.
0
So, let me just clarify.
lnx / x = 1/x?

Asylum15
Best Response
You've already chosen the best response.
0
Where does the x under the line go?

waterineyes
Best Response
You've already chosen the best response.
2
See :
\[\ln(x) = u\]
Right ??

Asylum15
Best Response
You've already chosen the best response.
0
Yes

waterineyes
Best Response
You've already chosen the best response.
2
Now take derivative both the sides and tell what did you get??

Asylum15
Best Response
You've already chosen the best response.
0
Next, i've been taught to do du/dx

Asylum15
Best Response
You've already chosen the best response.
0
1/x . dx

waterineyes
Best Response
You've already chosen the best response.
2
Write them properly..
with LHS and RHS..

Asylum15
Best Response
You've already chosen the best response.
0
Little lost here, sorry :(

Asylum15
Best Response
You've already chosen the best response.
0
1/x . dx = du

waterineyes
Best Response
You've already chosen the best response.
2
Do you know how it came??

Asylum15
Best Response
You've already chosen the best response.
0
Yes i get this.

Asylum15
Best Response
You've already chosen the best response.
0
What is the next step?

waterineyes
Best Response
You've already chosen the best response.
2
Just use this to substitute these values in your question..

Asylum15
Best Response
You've already chosen the best response.
0
I think the way i've been taught is conflicting...
I usually write dx = du / 1/x

Asylum15
Best Response
You've already chosen the best response.
0
If substituting