Math Problem Statement

solve

La valeur de l’intégrale \( \int_1^e \frac{\ln^2(x)}{x} \, dx \) est ?

Solution

To solve the given integral:

1eln2(x)xdx\int_1^e \frac{\ln^2(x)}{x} \, dx

We can use the substitution u=ln(x)u = \ln(x), which implies: du=1xdxandu ranges from ln(1)=0 to ln(e)=1.du = \frac{1}{x} dx \quad \text{and} \quad u \text{ ranges from } \ln(1) = 0 \text{ to } \ln(e) = 1.

The integral then transforms as follows: 1eln2(x)xdx=01u2du.\int_1^e \frac{\ln^2(x)}{x} \, dx = \int_0^1 u^2 \, du.

Solving the simplified integral:

01u2du=[u33]01=133033=13.\int_0^1 u^2 \, du = \left[ \frac{u^3}{3} \right]_0^1 = \frac{1^3}{3} - \frac{0^3}{3} = \frac{1}{3}.

Thus, the value of the integral is: 13\boxed{\frac{1}{3}}

This corresponds to option DD.


Would you like a detailed explanation of substitution or the integration process?
Here are 5 related questions to expand your understanding:

  1. How is substitution applied in integral calculus?
  2. What is the geometric interpretation of the integral in this problem?
  3. Can you solve ln(x)xdx\int \frac{\ln(x)}{x} \, dx and compare?
  4. What if the limits were different, such as [1,e2][1, e^2]?
  5. What is the connection between logarithmic functions and integration?

Tip: Always check the domain of functions like ln(x)\ln(x) before integrating to ensure the limits are valid!

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Math Problem Analysis

Mathematical Concepts

Integral Calculus
Substitution in Integration
Definite Integrals

Formulas

Substitution: \( u = \ln(x) \), \( du = \frac{1}{x} dx \)
Power Rule: \( \int u^n \, du = \frac{u^{n+1}}{n+1} + C \) for \( n \neq -1 \)

Theorems

Fundamental Theorem of Calculus

Suitable Grade Level

Grades 11-12 and Undergraduate