"答：y=x+1/x+3求导：y'(x)=1-1/x²令y'(x)=1-1/x²=0解得：x1=-1,x2=1当x<-1或者x>1时,y'(x)>0,y(x)是单调增函数当-1<x<0或者0<x<1时,y'(x)<0,y(x)是单调...