SOLUTION: I have trouble with these remaining problems i could use some help answering these thank you Geometric sequencing three of the five variables a1, an,

Algebra ->  Formulas -> SOLUTION: I have trouble with these remaining problems i could use some help answering these thank you Geometric sequencing three of the five variables a1, an,       Log On


   



Question 35529: I have trouble with these remaining problems i could use some help answering these thank you
Geometric sequencing
three of the five variables a1, an, r, n, and Sn are given. Find the two variables not given.
a1 = 10, r = 3, n = 5
a1 = 4, an = 324, r = 3
an = 24, r = , n = 4
Sn = 1022, r = 2, n = 9

Answer by venugopalramana(3286) About Me  (Show Source):
You can put this solution on YOUR website!
I have trouble with these remaining problems i could use some help answering these thank you
Geometric sequencing
three of the five variables a1, an, r, n, and Sn are given. Find the two variables not given.
FORMULAE ARE
AN=A1*R^(N-1)
SN=A1*(R^N -1)/(R-1)
a1 = 10, r = 3, n = 5......AN=10*3^(5-1)=810...SN =10*(3^5-1)/(3-1)=1210.
a1 = 4, an = 324, r = 3....324=4*3^(N-1)...N=5...SN=4*(3^5 -1)/(3-1)=484
an = 24, r = 2, n = 4....24=A1*2^(4-1)...A1=3...SN=3*(2^4 -1)/(2-1)=45
Sn = 1022, r = 2, n = 9 ...1022=A1(2^9 -1)/(2-1)=A1*(512-1)=511A1...A1=2
AN=2*2(9-1)=512