Friday, April 23, 2010

inverse of x*e^x

We are asked to find the inverse of :


One way to find an inverse is to start with the equation y=f(x); then exchange x and y and solve the result for y.



-----------



To get rid of the exponent, take the natural logarithm of each side:



Use properties of logarithms to simplify the right hand side:



Note that we cannot write this as a function of x using elementary functions.


----------------------------------------------------------------------------


The inverse  is called the Lambert W-function. If we assume that x is real and x>-1 we get a single valued function. Without this restriction, y=xe^x does not have an inverse function as it fails the horizontal line test.


The graph of :



We can draw the inverse relation by reflecting the graph over the line y=x.

No comments:

Post a Comment

find square roots of -1+2i

We have to find the square root of i.e. We will find the square roots of the complex number of the form x+yi , where ...