log_1/2 x
问题描述：
log_1/2 x
答
1/2=log(1/2)[(1/2)^(1/2)]
=log(1/2)[√(1/2)]
=log(1/2)[1/√2]
0所以=log(1/2)x是减函数
log(1/2)x所以x>=√2/2