2007 AMC 12A Problems/Problem 14

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Problem

Let a, b, c, d, and e be distinct integers such that

  • $(6-a)(6-b)(6-c)(6-d)(6-e)=45$

What is a+b+c+d+e?

  • (A) 5
  • (B) 17
  • (C) 25
  • (D) 27
  • (E) 30

Solution

If 45 is expressed as a product of five distinct integer factors, the absolute value of the product of any four it as least $|(-3)(-1)(1)(3)|=9$, so no factor can have an absolute value greater than 5. Thus the factors of the given expression are five of the integers $+-3, +- 1, +- 5$. The product of all six of these is -225=(-5)(45), so the factors are -3, -1, 1, 3, and 5. The corresponding values of a, b, c, d, and e are 9, 7, , 3, and 1, and their sum is 25 (C).


See also

2007 AMC 12A (ProblemsAnswer KeyResources)
Preceded by
Problem 13
Followed by
Problem 15
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
All AMC 12 Problems and Solutions