Math Is Fun Forum

ned13b

Guest

Finding the inverse function

I want to find the inverse function of:

f(x) = 2 + x + e^x

so far I have gotten to

x - 2 = y + e^y

the y with coefficient 1 makes it tough.  How can I isolate y?

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Finding the inverse function

Hi ned13b;

To get the inverse function you substitute y for f(x) and solve for x. That cannot be done in this case in terms of elementary functions, You would need to use something called the product log or Lambert function.

Please read this:

http://www.mathsisfun.com/sets/function-inverse.html

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