How do you find the first four terms of the geometric sequence for which a1=4 and r=3?

1 Answer
Dec 31, 2015

Answer:

If the first term is 4 and the common ratio (r) is 3, t

Explanation:

If the first term is 4 and the common ratio (r) is 3, then the second term must be 3 times the first time, since a geometric series is a repeated multiplication. Alternatively, you can use the formula for the nth of a geometric series, which will benefit when you're dealing with very large numbers such as finding #t_26# (the 26th term).

The following solution solves this problem using the formula:

#t_n# = a • #r^(n - 1)#

#t_4# = 4 • #3^(4 - 1)#

#t_4# = 4 • 27

#t_4# = 108

The 4th term is 108, and by logical deduction the 3rd term is 36, the second term 12 and the first term 4.

#t_1# = 4
#t_2# = 12
#t_3# = 36
#t_4# = 108