Math Problem Statement

Find the indefinite integral of \( \int \frac{x^2}{x - 9} \, dx \).

Solution

We are asked to find the indefinite integral of:

x2x9dx\int \frac{x^2}{x - 9} \, dx

To solve this, we can use long division to simplify the integrand.

Step 1: Long Division of x2x9\frac{x^2}{x - 9}

Perform the division of x2x^2 by x9x - 9:

x2÷(x9)=x+9+81x9x^2 \div (x - 9) = x + 9 + \frac{81}{x - 9}

So, we can rewrite the integral as:

(x+9+81x9)dx\int \left(x + 9 + \frac{81}{x - 9} \right) dx

Step 2: Integrate Term by Term

Now we can integrate each term:

  1. xdx=x22\int x \, dx = \frac{x^2}{2}
  2. 9dx=9x\int 9 \, dx = 9x
  3. 81x9dx=81lnx9\int \frac{81}{x - 9} \, dx = 81 \ln |x - 9|

Step 3: Combine the Results

The solution to the integral is:

x22+9x+81lnx9+C\frac{x^2}{2} + 9x + 81 \ln |x - 9| + C

Where CC is the constant of integration.


Would you like further details or have any questions about the steps?

Here are some related questions to expand on this concept:

  1. How does long division of polynomials work in general?
  2. Can this method be applied to rational functions with higher-degree polynomials?
  3. How can you recognize when to use logarithms in integrals?
  4. What other techniques exist for integrating rational functions?
  5. What is the importance of the constant of integration in indefinite integrals?

Tip: Always check if the degree of the numerator is greater than or equal to the denominator before deciding to use long division in integrals.

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Math Problem Analysis

Mathematical Concepts

Integration
Long Division of Polynomials
Logarithmic Integration

Formulas

Integral of \( \frac{x^2}{x - 9} \) using long division
Logarithmic Integral \( \int \frac{1}{x} \, dx = \ln |x| \)

Theorems

Integral of Polynomial Functions
Integral of Rational Functions

Suitable Grade Level

Grades 11-12