Question

Write an equation for the nth term of the given sequence. 8,72,648,...,a

Answer 1

notice :
72 =8*9
648 = 72*9
so, next term is 9 times the previous.
---> common ratio =r= 9
1st term = a1 = 8
Then the n'th term of given geometric progression will be
\[\large a_n=a_1.r^{n-1}\]
just put r and a1 values and you get your equation :)