3
a: =>\(\left(\dfrac{x+5}{2010}+1\right)+\left(\dfrac{x+4}{2011}+1\right)+\left(\dfrac{x+3}{2012}+1\right)< \left(\dfrac{x+9}{2006}+1\right)+\left(\dfrac{x+10}{2005}+1\right)+\left(\dfrac{x+11}{2004}+1\right)\)
=>x+2015<0
=>x<-2015
b: =>x+2>0 và x-5<0
=>-2<x<5
c: =>x-5>0 hoặc x-2<0
=>x<2 hoặc x>5
d: =>(4x-3-5x+5)/(x-1)<0
=>(-x+2)/(x-1)<0
=>(x-2)/(x-1)>0
=>x>2 hoặc x<1