Problem 11

Question

Find the indefinite integral. $$ \int \frac{(\ln x)^{2}}{x} d x $$

Step-by-Step Solution

Verified
Answer
The indefinite integral \(\int \frac{(\ln x)^{2}}{x} dx = \frac{1}{3}(\ln x)^3 + C\).
1Step 1: Identify Function for Substitution
Identify the inner function that makes the integral complex. Here, \(\ln x\) is such a function. We make a substitution such that \(u = \ln x\). This simplifies the integral. Differentiate \(u\) with respect to \(x\) to find \(du\), i.e., \(du = \frac{1}{x} dx\).
2Step 2: Replace in Integral
Replace \(\ln x\) and \(dx\) in the integral with \(u\) and \(du\) respectively. This transforms the integral into the much simpler form \(\int u^2 du\).
3Step 3: Integrate
Evaluate the integral \(\int u^2 du\). This is a basic power rule integral, and its antiderivative is \(\frac{1}{3}u^3 + C\), where \(C\) is the constant of integration.
4Step 4: Substitute Back
Finally, substitute \(u\) back into the integral. Since \(u = \ln x\), the final result of the integral is \(\frac{1}{3}(\ln x)^3 + C\).