Find the sum of the first 8 terms of the following sequence. Round to the nearest hundredth if necessary.64,80,100,…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.64,80,100,…Sum of a finite geometric series:Sn=1−ra1−a1rnAnswer:
Identify sequence type: First, identify the type of sequence given. The sequence 64,80,100,… suggests that it is an arithmetic sequence because the difference between consecutive terms is constant.
Determine common difference: Determine the common difference d of the arithmetic sequence by subtracting the first term from the second term: d=80−64=16.
Use sum formula: Use the formula for the sum of the first n terms of an arithmetic sequence: Sn=2n×(2a1+(n−1)d), where Sn is the sum of the first n terms, a1 is the first term, and d is the common difference.
Plug values into formula: Plug the values into the formula to find the sum of the first 8 terms: S8=28×(2×64+(8−1)×16).
Simplify expression: Simplify the expression: S8=4×(128+7×16)=4×(128+112)=4×240.
Calculate sum: Calculate the sum: S8=4×240=960.
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