2021 AMC 12B Fall Problem 4

Below is the professionally curated solution for Problem 4 of the 2021 AMC 12B Fall, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2021 AMC 12B Fall solutions, or check the answer key.

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Concepts:exponent

Difficulty rating: 1150

4.

Let n=82022.n = 8^{2022}. Which of the following is equal to n4?\dfrac{n}{4}?

410104^{1010}

220222^{2022}

820188^{2018}

430314^{3031}

430324^{3032}

Solution:

Write n=82022=26066.n = 8^{2022} = 2^{6066}. Then n4=2606622=26064.\dfrac{n}{4} = \dfrac{2^{6066}}{2^{2}} = 2^{6064}.

Since 26064=43032,2^{6064} = 4^{3032}, this matches the last option.

Thus, the correct answer is E.

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