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2002 AMC 10B Problem 11

Problem 11 of 25IntermediateAlgebra

The product of three consecutive positive integers is 88 times their sum. What is the sum of their squares?

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Solution

Let the integers be n−1,n - 1, n,n, n+1.n + 1. Their product is n(n2−1)n(n^2 - 1) and their sum is 3n,3n, so n(n2−1)=8(3n)=24n.n(n^2 - 1) = 8(3n) = 24n. Since n≠0,n \ne 0, we get n2−1=24,n^2 - 1 = 24, so n2=25n^2 = 25 and n=5.n = 5. The three integers are 4,4, 5,5, and 6,6, and 42+52+62=16+25+364^2 + 5^2 + 6^2 = 16 + 25 + 36 =77.= 77. Thus, the correct answer is B.
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