f=lg[(kx-1)/(x-1)]
设真数t=(kx-1)/(x-1)>0
函数f在【10,正无穷）上单调递增
需t=(kx-1)/(x-1)在【10,正无穷）上单调递增
k=0时,t=1/(1-x) 定义域为(-∞,1)不合题意
t=[(kx-k)+(k-1)]/(x-1)
=k+(k-1)/(x-1)
k>1时,
t=k+(k-1)/(x-1)在(1,+∞)上为减函数,不合题意
k=1f(x)=0,不合题意
00
解得x1/k
∵k-1
f=lg[(kx-1)/(x-1)]
设真数t=(kx-1)/(x-1)>0
函数f在【10,正无穷）上单调递增
需t=(kx-1)/(x-1)在【10,正无穷）上单调递增
k=0时,t=1/(1-x) 定义域为(-∞,1)不合题意
t=[(kx-k)+(k-1)]/(x-1)
=k+(k-1)/(x-1)
k>1时,
t=k+(k-1)/(x-1)在(1,+∞)上为减函数,不合题意
k=1f(x)=0,不合题意
00
解得x1/k
∵k-1