2003 AIME II Problem 1

Attempt Problem 1 of the 2003 AIME II below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2003 AIME II solutions, or check the answer key.

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1.

The product NN of three positive integers is 66 times their sum, and one of the integers is the sum of the other two. Find the sum of all possible values of N.N.

Answer: 336
Concepts:Diophantine Equationfactoring
Difficulty rating: 1840
Solution:

Let the integers be a,a, b,b, and c=a+b.c = a + b. Then N=abc=6(a+b+c)=62c=12c, \begin{aligned} N &= abc = 6(a + b + c) \\ &= 6 \cdot 2c = 12c, \end{aligned} and cancelling cc from abc=12cabc = 12c leaves ab=12.ab = 12.

The factorizations (a,b)=(1,12),(a, b) = (1, 12), (2,6),(2, 6), (3,4)(3, 4) give c=13,c = 13, 8,8, 77 and N=12c=156,N = 12c = 156, 96,96, 84.84. The sum of all possible values is 156+96+84=336.156 + 96 + 84 = 336.

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