2014 AMC 12A Problem 7 — Solution | LIVE by Po-Shen Loh

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2014 AMC 12A Problem 7

Below is the professionally curated solution for Problem 7 of the 2014 AMC 12A, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2014 AMC 12A solutions, or check the answer key.

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Concepts:geometric sequence exponent

Difficulty rating: 1340

7.

The first three terms of a geometric progression are $\sqrt{3},$ $\sqrt[3]{3},$ and $\sqrt[6]{3}.$ What is the fourth term?

$1$

$\sqrt[7]{3}$

$\sqrt[8]{3}$

$\sqrt[9]{3}$

$\sqrt[10]{3}$

Solution:

Writing the terms as powers of $3,$ they are $3^{1/2},$ $3^{1/3},$ $3^{1/6}.$ The common ratio is $\dfrac{3^{1/3}}{3^{1/2}}=3^{-1/6}.$

The fourth term is $3^{1/6}\cdot3^{-1/6}=3^{0}=1.$

Thus, the correct answer is A.

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