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anonymous
 one year ago
Find S7 for the geometric series 2 + 6 + 18 + 54 +…
i got 1450?
anonymous
 one year ago
Find S7 for the geometric series 2 + 6 + 18 + 54 +… i got 1450?

This Question is Closed

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Almost. What is the common ratio?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0So close. What about the change in sign every term?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Now, four terms are given, and you need the 7th term. So, take the 4th term (54) and multiply by the common ratio three more times. What do you get?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Not quite. \[54 \times 3 \times 3 \times 3 = ?\]

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I got 1458... that's not right though.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Why do you think it's incorrect?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0the answer choices are 162 486 1094 4374

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0OK. Perhaps it's a notation issue. Perhaps, when the questions asks for S7, what they want is the SUM of the first 7 terms. Could that be it?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0If so, to calculate the sum of the first n terms of a geometric series, use\[\sum_{i=1}^{n} a_i = a \left( \frac{ 1r^n }{ 1r } \right)\]where a is the 1st term, r is the common ratio, and n is the number of terms to be summed.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0That will give you the correct answer.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0\[S_7 = 2\left( \frac{ 1\left( 3 \right) ^7}{ 1\left( 3 \right) } \right) = ?\]
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