2009 AMC 10A Problem 13

Below is the professionally curated solution for Problem 13 of the 2009 AMC 10A, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2009 AMC 10A solutions, or check the answer key.

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Concepts:exponentprime factorization

Difficulty rating: 1280

13.

Suppose that P=2mP = 2^m and Q=3n.Q = 3^n. Which of the following is equal to 12mn12^{mn} for every pair of integers (m,n)?(m, n)?

P2QP^2 Q

PnQmP^n Q^m

PnQ2mP^n Q^{2m}

P2mQnP^{2m} Q^n

P2nQmP^{2n} Q^m

Solution:

Since 12=223,12 = 2^2 \cdot 3, 12mn=22mn3mn=(2m)2n(3n)m=P2nQm.12^{mn} = 2^{2mn} \cdot 3^{mn} = (2^m)^{2n} \cdot (3^n)^m = P^{2n} Q^m.

Thus, the correct answer is E.

Problem 13 in Other Years