1. Suppose {a_n} is a geometric sequence such that a_9=13, a_{13}=1. Find log_{a_1} 13=?
2. Suppose a>0. The minimum value of the function f(x)= x + 100/x on interval (0,a] is m; the minimum value of this function on interval [a, infty) is n. If mn=2020, what is the value of a
答案:1) 1/3
2)202 6park.com