x>1
x+ 1/(x-1)+1=(x-1)+ 1/(x-1)+2≥2+2=4
底数1/2<1,log1/2(U)内单调递减的,所以x+ 1/(x-1)+1取最大值时y取得最小值
当且仅当(x-1)=1/(x-1),得x=2时(x=0不取)
当x=2时,ymax=log1/2(4)=-2
x>1y
=
log
1/2
{x+1/(x-1)-1)}=
log
1/2
{(x-1)
+1/(x-1)}∵x-1>0∴(x-1)
+1/(x-1)
=
{根号(x-1)
-
1/根号(x-1)
}^2
+
2
≥
2
∵底数1/2
<1∴当真数(x-1)
+1/(x-1)取最小值时,y取最大值∴ymax
=
log
1/2
2
=
-1