Math Problem Statement

Evaluate the integral \( \int \left( \frac{1}{x} + 1 \right)^2 dx \).

Solution

To solve the integral (1x+1)2dx\int \left( \frac{1}{x} + 1 \right)^2 dx, let’s proceed step by step:

Step 1: Expand the square

(1x+1)2=1x2+21x+1\left( \frac{1}{x} + 1 \right)^2 = \frac{1}{x^2} + 2\frac{1}{x} + 1

So the integral becomes: (1x2+21x+1)dx\int \left( \frac{1}{x^2} + 2\frac{1}{x} + 1 \right) dx

Step 2: Separate the integral

(1x2+21x+1)dx=1x2dx+21xdx+1dx\int \left( \frac{1}{x^2} + 2\frac{1}{x} + 1 \right) dx = \int \frac{1}{x^2} dx + 2 \int \frac{1}{x} dx + \int 1 dx

Step 3: Compute each term

  1. First term: 1x2dx\int \frac{1}{x^2} dx Recall that 1x2=x2\frac{1}{x^2} = x^{-2}, so: x2dx=x11=1x\int x^{-2} dx = \frac{x^{-1}}{-1} = -\frac{1}{x}

  2. Second term: 21xdx2 \int \frac{1}{x} dx The integral of 1x\frac{1}{x} is lnx\ln|x|, so: 21xdx=2lnx2 \int \frac{1}{x} dx = 2 \ln|x|

  3. Third term: 1dx\int 1 dx The integral of 11 is xx, so: 1dx=x\int 1 dx = x

Step 4: Combine the results

(1x+1)2dx=1x+2lnx+x+C\int \left( \frac{1}{x} + 1 \right)^2 dx = -\frac{1}{x} + 2 \ln|x| + x + C

Where CC is the constant of integration.


Would you like me to expand on any part of this solution or verify using an alternate method? Here are some related questions to explore:

  1. What is the physical interpretation of logarithmic terms in integrals?
  2. How does the method of substitution work for similar rational integrals?
  3. What happens if we apply integration by parts to this problem?
  4. Could we solve this using definite integral bounds instead of indefinite?
  5. How do powers of 1x\frac{1}{x} behave as x0x \to 0 or xx \to \infty?

Tip: Always simplify your integrand when possible before integrating, as it often makes the process smoother!

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Math Problem Analysis

Mathematical Concepts

Integration
Expansion of Binomials
Indefinite Integrals

Formulas

Integral of a sum: \( \int (f(x) + g(x)) dx = \int f(x) dx + \int g(x) dx \)
Power rule for integration: \( \int x^n dx = \frac{x^{n+1}}{n+1} + C \) for \(n \neq -1\)
Integral of \( \frac{1}{x} \): \( \int \frac{1}{x} dx = \ln|x| + C \)

Theorems

Basic Properties of Integrals

Suitable Grade Level

Grades 11-12