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the first term of a geometric sequence is 2 and the common ratio is 3 find the sum of the first 5 terms

User DengSihan
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1 Answer

5 votes

Answer

(with step-by-step explanation):

[Find first the value of the 5th term.]

an = a1(r)^n-1

A5 = 2(3)^5-1 = 2(3)⁴ = 2(81) = 162

[Use the formula in finding sum of terms in Geometric Sequence]

Sn = [a1 - an(r)] / 1 - r

[Substitute the given values]

S5 = [2 - 162(3)] / 1 - 3

= 2-486 / -2 = -484/-2 = 242

• Therefore, the answer is Letter B, 242.

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