# Two functions converging

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• September 17th 2009, 06:45 AM
Amosino
Two functions converging
Hello!

Suppose i have two functions f(x) > g(x). I need that f(x) - g(x) = 0 (well, as close as possible to zero) from some point x* on. Does anyone know a condition to guarantee that?

Thanks in advance,

A.
• September 17th 2009, 07:07 AM
chisigma
The solution to your problem is the value x that minimizes the quantity...

$e(x) = f(x) - g(x)$ (1)

... which is one of the numbers $x$ that satisfies the equation...

$e^{'} (x)=0$ (2)

... with the further condition...

$e^{''} (x) > 0$ (3)

Kind regards

$\chi$ $\sigma$
• September 18th 2009, 04:51 AM
Amosino
Two Functions converging (Solved)
SURE!

Thank you very much for your help!

Best Regards,

A.