Help Evaluating integral (x^2 +2)/(x(x^2+5x+8))dx

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In summary, the topic of discussion was finding the easiest way to evaluate the integral (x^2 + 2)/(x(x^2 + 5x + 8))dx using partial fractions. One person shared their solution, which involved using logarithms. Another person pointed out that the numerator is not the derivative of the denominator, making the suggested method not applicable. The overall consensus was that this problem was difficult and took a long time to solve.
  • #1
GreenPrint
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Easier Way to Evaluate integral (x^2 +2)/(x(x^2+5x+8))dx

see the next post
Evaluate integral (x^2+2)/(x(x^2+5x+8)dx
 
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  • #2
So I got the right answer and wolfram alpha confirms it

http://www.wolframalpha.com/input/?i=d%5B1%2F4ln%28|x|%29-3%2F4ln%28|sqrt%287%29%2F%282sqrt%28%28x%2B+5%2F2%29^2%2B7%2F4%29%29|%29%2B%2825sqrt%287%29%29%2F28cot^%28-1%29%28%282x%2B5%29%2Fsqrt%287%29%29%5D%2Fdx

integral (x^2+2)/(x(x^2+5x+8)dx = -3 ln| sqrt(7)/(2 sqrt( (x+ 5/2)^ 2 + 7/4) ) | + (25*sqrt(7))/7 * cot^(-1)((2x+5)/sqrt(7)) +c

and this was the integration techniques partial fractions section of the book I'm using for calculus two

that was absolutely miserable and took me forever to do
see my work is attached to see how i solved it...

how do i solve this integral in a much easier way using partial fractions what's the easiest way to evaluate this knowing that this is only calculus 2
 

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  • #3
Easiest way:

[tex]\int{\frac{f'(x)}{f(x)}=ln(f(x))[/tex]
 
  • #4
icystrike said:
Easiest way:

[tex]\int\frac{f\,'(x)}{f(x)}=\ln(f(x))[/tex]
How does this help?

The numerator is not the derivative of the denominator.
 

FAQ: Help Evaluating integral (x^2 +2)/(x(x^2+5x+8))dx

What does "integral" mean in this context?

The integral in this context refers to the process of finding the area under a curve, also known as the antiderivative.

How do I evaluate this integral?

To evaluate this integral, you can use the method of partial fractions or substitution. Alternatively, you can also use online tools or calculator software to solve it.

Is there a specific range of values for x that I should use?

No, there is no specific range of values for x that you need to use. However, it is important to note any discontinuities or points of divergence in the given function.

Are there any special rules or formulas I need to know to solve this integral?

Yes, there are a few special rules and formulas that can be helpful in solving this integral, such as the power rule, quotient rule, and integration by parts.

Can I use the fundamental theorem of calculus to evaluate this integral?

Yes, you can use the fundamental theorem of calculus to evaluate this integral, as it states that the integral of a function is equal to the difference of its antiderivative evaluated at the upper and lower limits of integration.

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