Calculus 2 Help: How to Integrate 2/((x^2)-1)

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In summary, the conversation suggests using partial fractions to solve the integral of 2/((x^2)-1), which can be expanded as A/(x-1) + B/(x+1). To find A and B, the integral is multiplied by x^2-1 and evaluated for x=1 and x=-1. Finally, the integral of 1/x is needed to solve the problem.
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ashleyk
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Hi, I have calculus 2 in college right now and am drawing a complete blank and need to get my homework done. If I wanted to take the integral of 2/((x^2)-1)...what would I do or where would I start? Thanks!
 
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Use partial fractions.
 
  • #3
First, that 2 in front shouldn't bother you. Just do the integral without the 2, then multiply by 2.
[tex]\frac{1}{x^2- 1}= \frac{1}{(x-1)(x+1)}[/tex]
and that can be expanded by "partial fractions":
[tex]\frac{1}{x^2-1}= \frac{A}{x-1}+ \frac{B}{x+1}[/tex]
To find A and B, multiply both sides of that by x2-1 then let x= 1 and -1 in turn.

To integrate the resulting fractions, look up the integral of [itex]\frac{1}{x}[/itex].
 

1. What is the formula for integrating 2/((x^2)-1)?

The formula for integrating 2/((x^2)-1) is: ∫ 2/((x^2)-1) dx = ln |(x+1)/(x-1)| + C

2. How do I solve this integral using substitution?

To solve this integral using substitution, let u = x^2 - 1. Then, du = 2x dx. Substituting these values into the integral, we get: ∫ 2/((x^2)-1) dx = ∫ 1/u du = ln |u| + C = ln |x^2 - 1| + C

3. Can I use the power rule to solve this integral?

No, the power rule cannot be used directly to solve this integral. The power rule states that ∫ x^n dx = (x^(n+1))/(n+1) + C. However, in this case, the exponent of x is -2, which would result in a negative value for n+1, making the integral undefined.

4. Are there any other methods to solve this integral?

Yes, there are other methods to solve this integral such as using partial fractions or trigonometric substitutions. However, using substitution is the most straightforward and commonly used method.

5. Is there a special technique for integrating rational functions like 2/((x^2)-1) in Calculus 2?

Yes, there is a special technique called partial fractions that can be used to solve integrals of rational functions. This technique involves breaking down the rational function into simpler fractions to make integration easier. In this case, the integral 2/((x^2)-1) can be rewritten as 2/((x-1)(x+1)) and then solved using partial fractions.

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