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What is the sum of the geometric sequence -1, 6, -36... if there are 6 terms?

a) -558
b) 546
c) -666
d) 702

User Carena
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1 Answer

6 votes

Final answer:

The sum of the geometric sequence -1, 6, -36... with 6 terms is approximately 952.14.

Step-by-step explanation:

A geometric sequence is a sequence of numbers where each term is found by multiplying the previous term by a constant ratio. In this case, the ratio between consecutive terms is -6, since -1 * -6 = 6, and 6 * -6 = -36. Given that there are 6 terms in the sequence, we can find the sum using the formula:

S = a * (1 - r^n) / (1 - r)

where S is the sum of the sequence, a is the first term, r is the common ratio, and n is the number of terms.

Plugging in the values:

S = -1 * (1 - (-6)^6) / (1 - (-6))

S = -1 * (1 - 46656) / (1 + 6)

S = -1 * (-46655) / 7

S = 6665 / 7

S = 952.14

Therefore, the sum of the geometric sequence -1, 6, -36... with 6 terms is approximately 952.14.

User Kofi
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