已知函数f(x)的定义域是(0,+∞),当x>1时,f(x)1时,f(x)

1）证明f(x)在定义域上是减函数
任设x1>x2>0,则x1/x2>1,f(x1/x2)2
f(1/3)=f(根号3/3*根号3/3)=2f(根号3/3)=2
所以有:f(x)-f(1/(x-2))>=-f(1/3)
f(x)+f(1/3)>=f(1/(x-2))
f(x/3)>=f(1/(x-2))
减函数得:x/32
故:x(x-2)