Yesterday, the best answer is: .5^(3/x).  (Contributed by fire. Good Job!)
dnialh solved the puzzle at 15:20:32.398; length: 11
dnialh solved the puzzle at 15:20:43.277; length: 11
dnialh solved the puzzle at 15:20:44.184; length: 11
dnialh solved the puzzle at 15:21:01.566; length: 10
fire solved the puzzle at 18:10:45.937; length: 11
fire solved the puzzle at 18:11:31.902; length: 10