2004 AMC 10B Problem 5

Below is the professionally curated solution for Problem 5 of the 2004 AMC 10B, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2004 AMC 10B solutions, or check the answer key.

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Concepts:exponentoptimizationcasework

Difficulty rating: 1120

5.

In the expression cabd,c \cdot a^b - d, the values of a,b,c,a, b, c, and dd are 0,1,2,0, 1, 2, and 3,3, although not necessarily in that order. What is the maximum possible value of the result?

55

66

88

99

1010

Solution:

Setting d=0d = 0 removes the subtraction, so we maximize cabc \cdot a^b using 1,2,3.1, 2, 3.

Taking c=1,c = 1, a=3,a = 3, b=2b = 2 gives 32=9.3^2 = 9. The alternative 23=82^3 = 8 is smaller, and any assignment with c>1c \gt 1 forces a smaller power. The maximum is 9.9.

Thus, the correct answer is D.

Problem 5 in Other Years