f(x)=(x²+2x+3)/x的值域

问题描述:

f(x)=(x²+2x+3)/x的值域

f(x)=(x²+2x+3)/x
=x+3/x+2
|x+3/x|>=2√3
(1)x>0 f(x) >=2√3+2
(2)x