（x+3)/2<2 x+3<4 x<1 (x+2)/2>(x+3)/3 3x+6>2x+6 x>0所以 0(2) x-3(x-2)>=4 x-3x+6>=4 2x<=2 x<=1 1+2x/3>x-1 2>x/3 x<6所以 x<=1
