Question 159125
Im having a brain fart. Im trying to solve 3+9+27+..., find S10
tn=3+(10-1)(is 3 to power of 3?) I can't remember the rule for multiplying.Please help! 
t10=12(?)
t10= 
s10= [n(t1+tn)/2]
-------------
What are you trying to do?