Integrating x^2e^-3lnx: Tips and Tricks for Solving Tricky Integrals

  • Thread starter Thread starter shseo0315
  • Start date Start date
  • Tags Tags
    Integrate
shseo0315
Messages
19
Reaction score
0

Homework Statement


int((x^2)(e^-3lnx))

anyone tips for this?

Homework Equations


The Attempt at a Solution

 
Physics news on Phys.org
Hint:

<br /> e^{-3 \, \ln{(x)}} = e^{\ln{(x^{-3})}} = ?<br />
 
Dickfore said:
Hint:

<br /> e^{-3 \, \ln{(x)}} = e^{\ln{(x^{-3})}} = ?<br />

now I get int (x^2)(e^(1/x^3)) then? stuck here
 
You are wrong. What does e^{\ln{y}} equal to? Use the property that the (natural) logarithm is the inverse function of the (natural) exponential function.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
Back
Top