2016 AMC 10B Problem 2

Below is the professionally curated solution for Problem 2 of the 2016 AMC 10B, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2016 AMC 10B solutions, or check the answer key.

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Concepts:custom operationexponent

Difficulty rating: 870

2.

If nm=n3m2,n\heartsuit m=n^3m^2, what is 2442?\frac{2\heartsuit 4}{4\heartsuit 2}?

 14 \ \dfrac{1}{4}

 12 \ \dfrac{1}{2}

 1 \ 1

 2 \ 2

 4 \ 4

Solution:

For any nonzero a,b,a,b, we have abba=a3b2b3a2=ab.\dfrac{a\heartsuit b}{b\heartsuit a} = \dfrac{a^3b^2}{b^3 a^2} = \dfrac ab . Using a=2,b=4,a=2,b=4, we get that 24=12.\frac{ 2}{4} = \frac 12.

Thus, the correct answer is B .

Problem 2 in Other Years