Sunday, 28 June 2015

calculus - Differentiable function, not constant, f(x+y)=f(x)f(y), f(0)=2


Let f:RR a derivable function but not
zero, such that f(0)=2 and f(x+y)=f(x) f(y)

for all
x and y belongs R. Find f.





My first answer is f(x)=e2x, and I proved that there are not more functions like f(x)=abx by Existence-Unity Theorem (ODE), but I don't know if I finished.



What do you think about this sketch of proof's idea?



Thanks,



I'll be asking more things.

No comments:

Post a Comment

real analysis - How to find limhrightarrow0fracsin(ha)h

How to find limh0sin(ha)h without lhopital rule? I know when I use lhopital I easy get $$ \lim_{h\rightarrow 0}...