# integral of 1/((a-x)(b-x)) | Summary and Q&A

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March 22, 2015
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blackpenredpen
integral of 1/((a-x)(b-x))

## TL;DR

This content explains how to integrate a function using partial fractions, even without knowing the exact numbers involved.

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### Q: What is partial fraction integration and when is it used?

Partial fraction integration is a method used to simplify and integrate rational functions with linear factors in the denominator. It is used when a function's denominator cannot be easily factorized or when the degree of the numerator is greater than or equal to the degree of the denominator.

### Q: How do you determine the values of the partial fraction coefficients?

The speaker mentions using the "cover-up" method to determine the values of the partial fraction coefficients. By substituting a specific value (such as 8) for the variable in the denominator, the numerator's coefficient can be obtained by evaluating the original function at that value.

### Q: What happens when the linear factors in the denominator have different signs?

When the linear factors have different signs (e.g., a - B), the speaker suggests rearranging the subtraction to make it uniform (e.g., -1 over B - a). This rearrangement allows for factoring out a common term from the fractional expression, simplifying the integration process.

### Q: What are the final steps to integrate a function using partial fractions?

After determining the partial fraction coefficients, the speaker demonstrates integrating each fraction separately. The integration results in the natural logarithm (Ln) of the absolute value of the difference between the variable and the constant involved in each fraction. The final result is obtained by combining the integrated fractions and adding a constant of integration.

## Summary & Key Takeaways

• This content discusses the process of integrating a function with partial fractions when there are linear factors in the denominator.

• The speaker demonstrates how to determine the values of the partial fraction coefficients using a method called "cover-up."

• The content also explores a technique to factor out a common term in the partial fraction expression to simplify the integration process.