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Find the sum of the first 6 terms of the following sequence. Round to the nearest hundredth if necessary.

8,quad12,quad18,dots
Sum of a finite geometric series:

S_(n)=(a_(1)-a_(1)r^(n))/(1-r)
Answer:

Find the sum of the first 66 terms of the following sequence. Round to the nearest hundredth if necessary.\newline8,12,18, 8, \quad 12, \quad 18, \ldots \newlineSum of a finite geometric series:\newlineSn=a1a1rn1r S_{n}=\frac{a_{1}-a_{1} r^{n}}{1-r} \newlineAnswer:

Full solution

Q. Find the sum of the first 66 terms of the following sequence. Round to the nearest hundredth if necessary.\newline8,12,18, 8, \quad 12, \quad 18, \ldots \newlineSum of a finite geometric series:\newlineSn=a1a1rn1r S_{n}=\frac{a_{1}-a_{1} r^{n}}{1-r} \newlineAnswer:
  1. Identify sequence type: First, we need to identify the type of sequence we are dealing with. The given sequence is 8,12,18,8, 12, 18, \ldots 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)(r), we divide the second term by the first term.\newliner=128=1.5r = \frac{12}{8} = 1.5
  2. Calculate common ratio: Now that we have the common ratio, we can use the formula for the sum of the first nn terms of a geometric series, which is Sn=a1a1rn1rS_n = \frac{a_1 - a_1 \cdot r^n}{1 - r}, where a1a_1 is the first term and nn is the number of terms. We are looking for the sum of the first 66 terms, so n=6n = 6 and a1=8a_1 = 8.
  3. Use sum formula: Let's plug the values into the formula and calculate the sum of the first 66 terms.\newlineS6=(88×1.56)(11.5)S_6 = \frac{(8 - 8 \times 1.5^6)}{(1 - 1.5)}
  4. Calculate 1.561.5^6: Now we calculate 1.561.5^6.\newline1.56=11.3906251.5^6 = 11.390625
  5. Substitute in formula: Substitute the value of 1.561.5^6 into the formula.\newlineS6=(88×11.390625)(11.5)S_6 = \frac{(8 - 8 \times 11.390625)}{(1 - 1.5)}
  6. Calculate 8×11.3906258 \times 11.390625: Now we calculate 8×11.3906258 \times 11.390625.8×11.390625=91.1258 \times 11.390625 = 91.125
  7. Calculate numerator and denominator: Substitute the value into the formula.\newlineS6=891.12511.5S_6 = \frac{8 - 91.125}{1 - 1.5}
  8. Divide numerator by denominator: Now we calculate the numerator and the denominator separately.\newlineNumerator: 891.125=83.1258 - 91.125 = -83.125\newlineDenominator: 11.5=0.51 - 1.5 = -0.5
  9. Perform final division: Finally, we divide the numerator by the denominator to find the sum of the first 66 terms.S6=83.1250.5S_6 = \frac{-83.125}{-0.5}
  10. Perform final division: Finally, we divide the numerator by the denominator to find the sum of the first 66 terms.S6=83.1250.5S_6 = \frac{-83.125}{-0.5}Perform the division to get the final answer.S6=166.25S_6 = 166.25

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