Question 78519: 2) Use the geometric sequence of numbers 1, 3, 9, 27, … to find the following:
a) What is r, the ratio between 2 consecutive terms?
b) Using the formula for the nth term of a geometric sequence, what is the 10th term?
c) Using the formula for the sum of a geometric sequence, what is the sum of the first 10 terms?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Use the geometric sequence of numbers 1, 3, 9, 27, … to find the following:
a) What is r, the ratio between 2 consecutive terms?
Any two consecutive terms determine "r": r=3/1=3
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b) Using the formula for the nth term of a geometric sequence, what is the 10th term?
Formula: a(n)=a(1)[r^(n-1]
a(10)=1 [3^9]= 19683
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c) Using the formula for the sum of a geometric sequence, what is the sum of the first 10 terms?
10th term?
Formula: S(n)=a(1)[r^(n+1)-1/(r-1)]
S(10)= 1[3^11-1 /(3-1)]
S(10) = [177146/2 = 88573
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Cheers,
Stan H.
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