Derivatives of functions and equality of those functions

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SUMMARY

The discussion centers on the relationship between the derivatives of two functions, f(x) and g(x). It is established that if the derivatives are equal, specifically if \(\frac{df(x)}{dx} = \frac{dg(x)}{dx}\), this does not imply that f(x) equals g(x). The example provided, where f(x) = x² + 3 and g(x) = x² - 4, illustrates that the functions can differ by a constant. The conclusion is that equality of derivatives indicates that the functions are equal up to an additive constant.

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Niles
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Hi

I thought of something today coming home from school: If I have two arbitrary real functions f(x) and g(x) and I know that
[tex] \frac{df(x)}{x} = \frac{dg(x)}{dx}[/tex]
Does this imply that f(x)=g(x)?


Niles.
 
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i think you df(x)/dx for the right hand side

no, they might not be the same.

As an example f(x)=x^2 +3 and g(x) = x^2 - 4

What do you get for df(x)/dx and dg(x)/dx?
 


Yes, I meant dx, not x, in the denominator. Thanks for pointing that out.

OK, I see. So it must be correct up to an additive constant. Thanks.
 

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