The analytical formula for finding f(x) from (1) is as follows.

(1) even function

(2) the symmetry axis is x= 1(3) a function g(x) with a defined domain.

(4) Parameter A firstly analyzes the solution with x= 1 as the symmetry axis: ∵x= 1 as the symmetry axis ∴f(x)=f(2-x)∵x It is necessary to classify and discuss 2-x.