Univariate Optimisation

[mathshelpplease]

Hello,

I need to solve the problem:


So far I have,



But wanted to firstly ask how to show that this is strictly concave, and also wondered if I had made a mistake as 6 was a far lower x value than I was expecting.

Thank you.

 

[blamocur]

You can find properties of concave smooth functions here : https://en.wikipedia.org/wiki/Concave_function#Functions_of_a_single_variable
As for you answer, I am getting the same one.

 

[mathshelpplease]

You can find properties of concave smooth functions here : https://en.wikipedia.org/wiki/Concave_function#Functions_of_a_single_variable
As for you answer, I am getting the same one.

Thank you for your help.