Integral of x^3 e^(x^2)/(x^2+1)^2

So by using the fomula \int u dv = uv - \int v duwe can get the \int \frac {2x^3e^{x^2}}{(x^2+1)^2} dx = \frac {e^{x^2}}{(x^2+1)} +C In summary, to find the definite integral of (x^3*e^(x^2))/(x^2+1)^2, one approach is to use the formula \int u dv = uv - \int v du and solve for u and v by differentiating and integrating the terms. Another possibility is to use the quotient rule and integrate the resulting terms.
  • #1
bhatnv
6
0
how would i go about finding the definite integral of this (x^3*e^(x^2))/(x^2+1)^2
 
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  • #2
bhatnv said:
how would i go about finding the definite integral of this [PLAIN]http://www.texify.com/img/%5CLARGE%5C%21f%28x%29%3D%5Cfrac%7Bx%5E3e%5Ex%5E2%7D%7B%28x%5E2%2B1%29%5E2%7D.gif[/QUOTE]
Your integral doesn't show up.
 
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  • #3
there, originally had a image so it would be easier to read the equation, but i guess it got taken down
 
  • #4
Here are a couple of possibilities for you to explore:
1) u = x^2/(x^2 + 1)^2, dv = xe^(x^2)dx

2) u = x^2 e^(x^2), dv = x/(x^2 + 1)^2

I tried the first one, and it got pretty messy, so I don't think that's it.
 
  • #5
By looking at
[tex]\frac{x^3 e^{x^2}}{(x^2+1)^2}[/tex]
we can see its in the form of quotient rule because the [tex] (x^2+1)^2[/tex] at the bottom.
note that [tex] D_x [e^{x^2}] = 2x e^{x^2} [/tex] and we can get the [tex]x^3 e^{x^2}[/tex] term when we differentiate [tex] \frac{e^{x^2}}{x^2+1}[/tex]


so the solution must be related to [tex]\frac {e^{x^2}}{x^2+1}[/tex]

[tex]D_x [\frac {e^{x^2}}{x^2+1}] = \frac {e^{x^2}2x(x^2+1)-2xe^{x^2}}{(x^2+1)^2} = \frac {2x^3e^{x^2}}{(x^2+1)^2} [/tex]
 

1. How do you solve the integral of x^3 e^(x^2)/(x^2+1)^2?

To solve this integral, we can use the substitution method. Let u = x^2+1, then du = 2x dx. Rearranging, we get x dx = du/2. Substituting this into the integral, we get 1/2 * ∫ e^u/ u^2 du. This integral can be solved using integration by parts, and the final result will be 1/2 * e^u/u + C. Substituting back in for u, we get the final answer of 1/2 * e^(x^2+1)/(x^2+1) + C.

2. What is the domain of the function x^3 e^(x^2)/(x^2+1)^2?

The domain of this function is all real numbers except for x = ±i, where i is the imaginary unit. This is because the denominator (x^2+1)^2 cannot be equal to 0, and the exponential function is defined for all real numbers.

3. Is the integral of x^3 e^(x^2)/(x^2+1)^2 an elementary function?

No, the integral of x^3 e^(x^2)/(x^2+1)^2 is not an elementary function. It cannot be expressed in terms of elementary functions such as polynomials, exponentials, logarithms, trigonometric functions, etc. This can be seen by trying to integrate it using the standard integration techniques, which will lead to a dead end.

4. Can the integral of x^3 e^(x^2)/(x^2+1)^2 be approximated numerically?

Yes, the integral can be approximated numerically using methods such as the trapezoidal rule or Simpson's rule. These methods use a series of small trapezoids or parabolas to approximate the area under the curve, and as the number of trapezoids or parabolas increases, the approximation becomes more accurate.

5. What applications does the integral of x^3 e^(x^2)/(x^2+1)^2 have in real life?

This integral has applications in various fields such as physics, engineering, and economics. For example, it can be used to calculate the work done by a variable force, the heat transfer in a system, or the area under a demand curve in economics. It is also used in statistics to calculate probabilities in a normal distribution. In general, integrals are used to model and solve real-world problems that involve continuous change.

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