当 x = y 时:f(y) + 2f(1/y) = 3y *当 x = 1/y 时:f(1/y) + 2f(y) = 3/y 2f(1/y) + 4f(y) = 6/y **两式相减得:-3f(y) = 3y - 6/yf(y) = 2/y -y即:f(x) = 2/x - x PS:关于补充,可以这样理解.x = 1/y 代入表达式.老师...