Question

用赋值法求函数值域比如：f（x）+3f（1/x）=2x,求f（x）解析式

Answer 1

f（x）+3f（1/x）=2x (1)

令x=1/x

f（1/x）+3f（x）=2/x (2)

(2)×3-(1)

8f(x)=6/x-2x=(6-2x²)/x

f(x)=(3-x²)/(4x)