SOLUTION: Given the following, solve for the unknown quantity. 1. Given:S4=120,r=3;find a1. 2. Given:S5=496,r=1/2;find a1. sn=sum of the number r=common ratio a1=first term

Question 1185483: Given the following, solve for the unknown quantity.

1. Given:S4=120,r=3;find a1.
2. Given:S5=496,r=1/2;find a1.
sn=sum of the number
r=common ratio
a1=first term
Answer by ikleyn(52818) (Show Source): You can put this solution on YOUR website!
.

Part 1

a + 3a + 9a + 27a = 120


40a = 120


a = 120/40 = 3.    ANSWER

Part 2

 +  +  +  +  = 496


 +  +  +  +  = 496


 = 496


a =  = 256.    ANSWER

Solved.

RELATED QUESTIONS
find a1 and the common ratio(r). given an=1, n=7,... (answered by MathLover1)

Hello, I am stuck with this problem and cannot seem to find any help. I need to find... (answered by ewatrrr)

I have trouble with these remaining problems i could use some help answering these thank... (answered by venugopalramana)

My problem is to find the indicated term for the geometric series described : Sn=33... (answered by Theo)

ARITHMETIC SERIES - Sn=n/2(a1 + an) Find the sum of the terms of the following... (answered by Edwin McCravy)

Find the Sn of the given artithmetic series. a1=-100, d=-1,... (answered by ikleyn)

Using this formula sn=a1 (1-rN)�1-r. Find the sum of... (answered by ewatrrr)

Use the formula for the general term (the nth term) of a geometric sequence to find the... (answered by MathLover1)

Find the sum of a geometric series for which a1 = 48, an = 3, and r = -1/2:... (answered by stanbon)