Find the sum of the first 8 terms of the following sequence. Round to the nearest hundredth if necessary.16,−8,4,…Sum of a finite geometric series:Sn=1−ra1−a1rnAnswer:
Q. Find the sum of the first 8 terms of the following sequence. Round to the nearest hundredth if necessary.16,−8,4,…Sum of a finite geometric series:Sn=1−ra1−a1rnAnswer:
Identify Sequence Type: Identify the type of sequence.The given sequence is a geometric sequence because each term is obtained by multiplying the previous term by a common ratio r.
Determine First Term and Ratio: Determine the first term (a1) and the common ratio (r).The first term a1 is 16. To find the common ratio, divide the second term by the first term: r=(−8)/16=−1/2.
Use Geometric Series Formula: Use the formula for the sum of the first n terms of a geometric series.The formula is Sn=1−ra1−a1⋅rn, where Sn is the sum of the first n terms, a1 is the first term, r is the common ratio, and n is the number of terms.
Plug Values into Formula: Plug the values into the formula to find the sum of the first 8 terms.S8=1−(−21)16−16×(−21)8
Calculate Sum: Calculate the sum.S8=(16−16×(1/256))/(1+1/2)S8=(16−1/16)/(3/2)S8=(256/16−1/16)/(3/2)S8=(255/16)×(2/3)S8=255/24S8=10.625
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