Let f : R → R, Such That f’ (0) = 1 and f (x +2y) = f (x) + f (2y) + Ex+2y (x + 2y) – x. Ex – 2y. E2y + 4xy, ∀ x, y Ïµ R. Find f (x).

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Question

Let f : → R, such that f’ (0) = 1 and f (x +2y) = f (x) + f (2y) + ex+2y (x + 2y) – x. ex – 2y. e2y + 4xy∀ xy Ïµ R. Find f (x).

Solution

Correct option is

We have, 

            

Replacing xy → 0, we get;   

           f (0) = f (0) + f (0) + 0 – 0 – 0 + 0 ⇒ f (0) = 0 

Replacing 2y → –x, we get;  

             

      

                     

  

                    

  

  

  

                     

Integrating (ii) both sides, 

       

                 

                

But    f (0) = 0 ⇒ c = 0 

So,    f (x) = x2 + x.ex

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