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What is the value of integral $\ln x$? Example:

$$\int_2^4 \left(5x^4+2x+5+2\ln x +{1\over x}\right)\,dx$$

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have you tried wikipedia? –  user31280 Nov 14 '12 at 14:19
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en.wikipedia.org/wiki/… –  user31280 Nov 14 '12 at 14:20
    
I can't find it on wikipedia –  lambda23 Nov 14 '12 at 14:21
    
i just posted a link as comment –  user31280 Nov 14 '12 at 14:21

2 Answers 2

up vote 3 down vote accepted

I guess what you are looking for is an antiderivative of $\ln(x)$. It is $$ \int \ln(x) \; dx = x\ln(x) -x +C. $$

This should allow you do find the integral.

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Hint: use integration by parts.

Another hint is greyed out below (hover over the box to show it, but only after you've tried!)

$\displaystyle \int \ln x\, dx = \int (1 \times \ln x)\, dx$

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