Find the first term of a geometric sequence whose 4th term is 108 and 7th term is 2 916.
Share
Find the first term of a geometric sequence whose 4th term is 108 and 7th term is 2 916.
Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Answer:
The 1st term is 4
Step-by-step explanation:
Linear sistem :
A1 × Q^6 = 2916
A1 × Q^3 = 108
__________________
(A1 × Q^6)/(A1 × Q^3) = 2916/108
Q^3 = 27
Q = ³√27
Q = 3
Find the 1st term :
An = A1 × Q^(n - 1)
108 = A1 × 3^(4 - 1)
108 = A1 × 3^(3)
108 = A1 × 27
A1 × 27 = 108
A1 = 108/27
A1 = 4
PG = {4 ,12 ,36 ,108 ,324 ,972 ,2916}.
Therefore , the 1st term is 4