f(x)+f(1/x)
=x^2/(1+x^2) +1/x^2/(1+1/x^2)
=x^2/(1+x^2) + 1/(1+x^2) (分子分母都乘以x^2)
=(x^2+1)/(1+x^2)
=1
所以f(2)+f(1/2) =1
f(3)+f(1/3) =1
f(4)+f(1/4) =1
f(1)=1/2
累加为 7/2
f(x)+f(1/x)
=x^2/(1+x^2) +1/x^2/(1+1/x^2)
=x^2/(1+x^2) + 1/(1+x^2) (分子分母都乘以x^2)
=(x^2+1)/(1+x^2)
=1
所以f(2)+f(1/2) =1
f(3)+f(1/3) =1
f(4)+f(1/4) =1
f(1)=1/2
累加为 7/2