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Back to derivative basics (Posted on 2024-01-22) Difficulty: 3 of 5
Find all functions f:R+->R satisfying:

f(1)=1,
f has second derivative and
f'(1/x)=-(1/2)f(x).

No Solution Yet Submitted by Danish Ahmed Khan    
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a thought... | Comment 1 of 2
This works except for a sign change: 

f(x) = c x^(1/2)

f'(x)   =  (c/2) x^(-1/2)  

f'(1/x) = (c/2) x^(-1/2) = (1/2) f(x), but not -(1/2) f(x) 

Edited on January 23, 2024, 8:58 am
  Posted by Steven Lord on 2024-01-23 05:32:44

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