[填空题]
The second and the tz 1,vefnet 5ya6c2w*p 4 ) bao2u:6: ubedsivdqi2f0third terms of a geometric sequence are $u_2$=3 and $u_3$=6.
1.Find the value of r, the common ratio of the sequence.
r= .
2.Find the value of $u_6$.
$u_6$= .
3.Find the largest value of n for which $u_n$ is less than $10^4$.
n= .