Evaluating Integral: \int\frac{4}{x^2-1}

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In summary, an integral is a mathematical concept used to calculate the area under a curve and the accumulation of a quantity over a given interval. Evaluating an integral involves finding an anti-derivative of the function and can be done using methods such as substitution or integration by parts. The specific integral \int\frac{4}{x^2-1} is used to calculate the area under a function of the form \frac{4}{x^2-1} and can also be used to calculate the total amount of a quantity that follows this function. A singularity in an integral is a point where the function being integrated becomes undefined or goes to infinity. The integral \int\frac{4}{x^2-1}
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danielatha4
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Homework Statement


[tex]\int[/tex][tex]\frac{4}{x^2-1}[/tex]



Homework Equations





The Attempt at a Solution


I thought I had this right...

[tex]\frac{4}{x^2-1}[/tex] = 2 ([tex]\frac{1}{x-1}[/tex]-[tex]\frac{1}{x+1}[/tex])

therefore,

[tex]\int[/tex][tex]\frac{4}{x^2-1}[/tex]=2(ln(x-1)-ln(x+1))

I then have to evaluate from 2 to 3 and I get .814, but it isn't right.
 
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  • #2
Nevermind, I believe I figured it out.

Edit: Okay, I don't understand where I went wrong. Any help please?
 
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  • #3
I get log(9/4) ≈ 0.81093
Perhaps you entered it wrong in a calculator?
 
  • #4
Oh gees... rounding error... thanks
 

FAQ: Evaluating Integral: \int\frac{4}{x^2-1}

What is an integral?

An integral is a mathematical concept that represents the area under a curve in a graph. It is used to calculate the total amount or accumulation of a quantity, such as distance, velocity, or mass, over a given interval.

What is the process for evaluating an integral?

The process for evaluating an integral involves finding an anti-derivative of the given function, which is a function whose derivative is the original function. This can be done using various methods such as integration by substitution, integration by parts, or using a table of integrals.

What is the specific integral \int\frac{4}{x^2-1} used for?

This integral is used to calculate the area under the curve of a function that has the form of \frac{4}{x^2-1}. It can also be used to calculate the total amount of a quantity that follows this function, such as the total work done by a variable force.

What is a singularity in an integral?

A singularity in an integral is a point where the function being integrated becomes undefined or goes to infinity. In the integral \int\frac{4}{x^2-1}, the points x=1 and x=-1 are singularities because the function becomes undefined at these points.

How can the integral \int\frac{4}{x^2-1} be evaluated?

The integral \int\frac{4}{x^2-1} can be evaluated using the substitution method. Let u = x^2-1, then du = 2x dx. Substituting these values into the integral gives \int\frac{4}{u}du. This can then be solved using the power rule for integration, giving the final answer of 4ln|u| + C.

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