log4 9=2lg3/2lg2 =lg3/lg2=log2 3
log2 3+log4 9+log8 27+...+log2^n 3^n
=nlog2 3=nlg3/lg2
log9 32的N次方根
(log2 3+log4 9+log8 27+...+log2^n 3^n）log9 32的N次方根=(1/n)(5lg2/2lg3)*nlg3/lg2
=5/2