VarL works differently for different actions

[Pushparaj Chakravarti]

Hi,

I am trying to get the field equations in f(R) gravity but I am not recovering the right field equations as in the textbook. By using the VarL command I am getting extra terms with double and triple derivatives of f(R) with respect to R. 

The Lagrangian I used is L= \sqrt[-g] f(R). The required answer should be as given in https://en.wikipedia.org/wiki/F(R)_gravity. I have attached the notebook below.

Cheers,

Pushparaj

[Asghar Muhammad]

I will attach note book of EqM of F(r) in standard text book form

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