I think you botched what  equals because  is just ,
and if  were merely , then  would just be the same as
 which would be , and that would be a silly
problem.


So I will make up something else for , since I don't believe
you really meant . Suppose the problem were

let  and . what is ?

Then  would have to be a quadratic function, say 



Then 







Rearrange the terms:



Factor x out of the 2nd and 3rd terms on the right



Since , we equate coefficients:



Substitute  into 





Substitute  and  into











So 

becomes

 

Edwin