I have problems with a variable that is given only implicitly. Maple provides incorrect answers but I am not sure where I make the mistake. Thanks for any comments! Here is what I do:

(1) I use "assume" to set properties of two paramters a and b.

> assume(a > 1);
> assume(b > 1);

(2) Since the variable "x" is given only implicitly, I define an implicit function following the description in the thread "How to define an implicit function in Maple?".