- #1
Ryan000
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Homework Statement
In the book it gave the example for standard change of variables as,
z = x / 1 + x or equivalently x = z / 1 - z , then
dx = dz / (1 - z)^2 , thus (2)
1 / (1 - z)^2 f (z / 1 - z) dz (3)
This is what I am trying to accomplish but with the expression x^3 / (e^x - 1) dx. So I can put this expression equal to z and find equivalent equal to x then find dx eq(2) then final result eq (3).
Homework Equations
integral of f(x) dx
The Attempt at a Solution
I found the derivative to be (3*x^2/(e^x - 1)) - (x^3 * e^x / (e^x - 1)^2) but not getting the final result like in equation (3) from above maybe I am doing change of variables wrong. I have seen the formulas with variables online but still not getting it. If someone could help that would be GREAT!