A = {$ f: R a R $}
with the following properties
f has derivative of each order
$ for all x, y in R $ $ f (x + y) -f (y-x) = 2xf & # 39; (y) $
so I have to find the whole family
So far I can only show $ f (x) -f (-x) / 2x = 2xf & # 39; (0) $
I wanted to solve this problem.
Please provide only clue …
Thanks in advance