Find the sum of the first 6 terms of the following sequence. Round to the nearest hundredth if necessary.8,12,18,…Sum of a finite geometric series:Sn=1−ra1−a1rnAnswer:
Q. Find the sum of the first 6 terms of the following sequence. Round to the nearest hundredth if necessary.8,12,18,…Sum of a finite geometric series:Sn=1−ra1−a1rnAnswer:
Identify sequence type: First, we need to identify the type of sequence we are dealing with. The given sequence is 8,12,18,… which seems to be a geometric sequence where each term is multiplied by a common ratio to get the next term. To find the common ratio (r), we divide the second term by the first term.r=812=1.5
Calculate common ratio: Now that we have the common ratio, we can use the formula for the sum of the first n terms of a geometric series, which is Sn=1−ra1−a1⋅rn, where a1 is the first term and n is the number of terms. We are looking for the sum of the first 6 terms, so n=6 and a1=8.
Use sum formula: Let's plug the values into the formula and calculate the sum of the first 6 terms.S6=(1−1.5)(8−8×1.56)
Calculate 1.56: Now we calculate 1.56.1.56=11.390625
Substitute in formula: Substitute the value of 1.56 into the formula.S6=(1−1.5)(8−8×11.390625)
Calculate 8×11.390625: Now we calculate 8×11.390625.8×11.390625=91.125
Calculate numerator and denominator: Substitute the value into the formula.S6=1−1.58−91.125
Divide numerator by denominator: Now we calculate the numerator and the denominator separately.Numerator: 8−91.125=−83.125Denominator: 1−1.5=−0.5
Perform final division: Finally, we divide the numerator by the denominator to find the sum of the first 6 terms.S6=−0.5−83.125
Perform final division: Finally, we divide the numerator by the denominator to find the sum of the first 6 terms.S6=−0.5−83.125Perform the division to get the final answer.S6=166.25
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