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In Exercises \(25-46,\) use substitution to evaluate the integral. $$\int \frac{d x}{x \ln x}$$

Short Answer

Expert verified
The integral \(\int \frac{dx}{x \ln x}\) evaluates to \(\ln |\ln x| + C\).

Step by step solution

01

Choose a substitution

Given the integral, make the substitution \(u = \ln x\), which simplifies the denominator. Consequently, the differential, \(du\), is equal to \(\frac{1}{x} dx.\)
02

Rewrite the Integral

Replace the instances of \(x\) in terms of \(u\) and \(dx\) in terms of \(du\) in the integral. This results in the following equivalent integral: \(\int \frac{du}{u}.\)
03

Evaluate the Integral

The integral \(\int du/u\) is a basic and standard integral that equals \(\ln |u|\) plus the constant of integration, \(C\). So, the integral simplifies to \(\ln |u| + C\).
04

Substitute back for \(x\)

Now, replace \(u\) with \(\ln x\) as per the original substitution. So, the answer is \(\ln |\ln x| + C\).

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Most popular questions from this chapter

Multiple Choice If \(\int x^{2} \cos x d x=h(x)-\int 2 x \sin x d x,\) then \(h(x)=\) (A) \(2 \sin x+2 x \cos x+C\) (B) \(x^{2} \sin x+C\) (C) \(2 x \cos x-x^{2} \sin x+C\) (D) \(4 \cos x-2 x \sin x+C\) (E) \(\left(2-x^{2}\right) \cos x-4 \sin x+C\)

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