Question

当X分别取1/2007,1/2006,.1/2,1.2005,2006,2007时,求1-X^2/1+X^2的所有值的和

Answer 1

f(x)=1-x^2/(1+x^2)=1/(1+x^2);

f(1/x)=x^2/(1+x^2)

则

f(x)+f(1/x)=1;

由上得答案是2007