Mastering Integration Techniques: Solving Intx2(1-5x2)10dx with Expert Help

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The discussion focuses on solving the integral \int x^2(1-5x^2)^{10}dx. The user explored various techniques including substitution, integration by parts, and trigonometric substitution, specifically using x = \frac{1}{\sqrt{5}} \cos(\theta). This approach transformed the integral into - \frac{1}{25} \int \cos^2(\theta) \sin^{21}(\theta)d\theta, which can be further simplified using a table of integrals. An alternative suggestion was to expand the integrand using the binomial theorem to facilitate integration.

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Dell
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need urgent help with this

any ideas will be appreciated

[tex]\int[/tex]x2(1-5x2)10dx

tried all kinds of things, what i now think needs to be done is to change the differential to d(1-5x2) so that i won't have to open the (1-5x2)10 which i really don't want to nor do i think i am expected to.

d(1-5x2)=-10xdx... not really helping me :(
 
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I tried several approaches, among them substitution and integration by parts, but didn't seem to get anywhere with either of these.

Another approach that seems promising is a trig substitution, using x = 1/sqrt(5) * cos(theta).

Using this approach I was able to rewrite the integral as
[tex]-1/25 \int cos^2(\theta) sin^{21}(\theta)d\theta[/tex]
This could be rewritten as two integrals, both in powers of sin(theta). At that point, I would use a table of integrals.

This approach might be beyond your present capabilities, but it's the only one I can think of that leads anywhere.
 


Dell said:
any ideas will be appreciated

[tex]\int[/tex]x2(1-5x2)10dx

tried all kinds of things, what i now think needs to be done is to change the differential to d(1-5x2) so that i won't have to open the (1-5x2)10 which i really don't want to nor do i think i am expected to.

d(1-5x2)=-10xdx... not really helping me :(
You could just expand the integrand using the binomial theorem.
 

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