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Give-a-function-f-R-0-continous-on-R-and-such-that-f-x-y-f-x-f-y-a-Prove-f-0-1-b-Let-h-x-ln-f-x-Prove-that-h-x-y-h-x-h-y-c-Find-all-the-function-f-such-that-problem-re




Question Number 199167 by tri26112004 last updated on 28/Oct/23
Give a function   f: R→(0;+∞) continous on R and such that  f(x+y) = f(x).f(y)  a. Prove f(0) = 1  b. Let h(x) = ln[f(x)]. Prove that:   h(x+y) = h(x) + h(y)  c. Find all the function f such that problem request
Giveafunctionf:R(0;+)continousonRandsuchthatf(x+y)=f(x).f(y)a.Provef(0)=1b.Leth(x)=ln[f(x)].Provethat:h(x+y)=h(x)+h(y)c.Findallthefunctionfsuchthatproblemrequest
Answered by AST last updated on 28/Oct/23
a.f(0)=[f(0)]^2 ⇒f(0)=0 or 1 but f(0)≠0⇒f(0)=1  b. h(x+y)=In[f(x+y)]=In[f(x).f(y)]  =In[f(x)]+In[f(y)]=h(x)+h(y)  c. e^(h(x)) =f(x) for continuous h(x)  Or generally, a^(h(x))  for continuous h(x)  where a>1
a.f(0)=[f(0)]2f(0)=0or1butf(0)0f(0)=1b.h(x+y)=In[f(x+y)]=In[f(x).f(y)]=In[f(x)]+In[f(y)]=h(x)+h(y)c.eh(x)=f(x)forcontinuoush(x)Orgenerally,ah(x)forcontinuoush(x)wherea>1
Commented by tri26112004 last updated on 28/Oct/23
Thank you so much!
Thankyousomuch!

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