- #1

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## Homework Statement

The integral from 1 to infinity of (lnx)/(x) dx

## Homework Equations

U substitution and integration by parts

## The Attempt at a Solution

Cant decide what to use as my "u" . . can any one help with this part ?

-Jay J-

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- Thread starter Jay J
- Start date

- #1

- 26

- 0

The integral from 1 to infinity of (lnx)/(x) dx

U substitution and integration by parts

Cant decide what to use as my "u" . . can any one help with this part ?

-Jay J-

- #2

kreil

Gold Member

- 668

- 67

[tex]\int \frac{ln(x)}{x}=\int u du = \frac{1}{2}u+ C= \frac{1}{2}(ln(x))^2+C[/tex]

here you take u = ln(x) and differentiate to get, du = 1/x dx.

- #3

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-Jay J-

- #4

Dick

Science Advisor

Homework Helper

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Evaluate the integral between x=0 and x=M and let M approach infinity. What do you conclude?

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