For which of the following functions f is f(x)= f(1-x) for all x?
*f(x)= 1-x
*f(x)= 1-x^2
*f(x)=x^2 - (1-x)^2
*f(x)=x^2 (1-x)^2
*f(x)=x/ 1-x
*f(x)= 1-x
*f(x)= 1-x^2
*f(x)=x^2 - (1-x)^2
*f(x)=x^2 (1-x)^2
*f(x)=x/ 1-x
