Given 3, 6, 12, 24,..., which term number is 384?

1 Answer
Mar 7, 2016

Answer:

8th term

Explanation:

Consider the standard geometric sequence :

a , ar , #ar^2 , ar^3 , ar^4 ,...................... , ar^(n-1)#

the nth term = #ar^(n-1) #

here a = 3 (1st term ) , #r = 6/3 = 12/6 =.....= a^n/a^(n-1) = 2#

want to find n where nth term = 384

solve : # ar^(n-1) = 384 rArr 3(2)^(n-1) = 384 #

hence # 2^(n-1) = 384/3 = 128 #

now # 2^(n-1) = 2^7 rArr n-1 = 7 rArr n = 8 #