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Evaluate the integral `int(p^2)(lnp)dp`

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user6978788 | Student, Undergraduate | Honors

Posted February 1, 2013 at 3:53 PM via web

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Evaluate the integral `int(p^2)(lnp)dp`

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justaguide | College Teacher | (Level 2) Distinguished Educator

Posted February 1, 2013 at 5:18 PM (Answer #1)

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The integral `int p^2*ln(p) dp` has to be determined.

Let `ln(p) = y => p = e^y` , `p*dy = dp`

`int p^2*ln(p) dp`

=> `int e^(2y)*y*e^y dy`

=> `int e^(3y)*y*dy`

Use integration by parts, let u = y and v = e^(3y)

=> `y*e^(3y) - int e^(3y) dy`

=> `y*e^(3y) - e^(3y)/3`

substitute y = ln(p)

=> `ln(p)*e^(ln p^3) - (e^(lnp^3))/3`

=> `ln(p)*p^3 - p^3/3`

The integral `int p^2*ln(p) dp = ln(p)*p^3 - p^3/3 + C`

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user6978788 | Student , Undergraduate | Honors

Posted February 5, 2013 at 4:15 AM (Answer #2)

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Actually, the answer should be `1/3` x(what you got there)

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