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Functional equation

Posted: Thu Apr 09, 2015 6:45 pm
by joy_li
I tried to solve $f(x-y)=f(x)+f(y)$ and found $f(x) = -cx$
(the process i followed is in the first comment)
but this gives
$-c(x-y) = -cx-cy$
$\Rightarrow -c(x-y) \neq -cx-cy $
someone please help me where did i go wrong :cry:

Re: Functional equation

Posted: Wed Apr 15, 2015 12:43 am
by nayel
joy_li wrote:$\Rightarrow -c(x-y) \neq -cx-cy$
Why? What if $c=0$?