14th USAMO 1985

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1.  Do there exist 1985 distinct positive integers such that the sum of their squares is a cube and the sum of their cubes is a square?
2.  Find all real roots of the quartic x4 - (2N + 1)x2 - x + N2 + N - 1 = 0 correct to 4 decimal places, where N = 1010.
3.  A tetrahedron has at most one edge longer than 1. What is the maximum total length of its edges?
4.  A graph has n > 2 points. Show that we can find two points A and B such that at least [n/2] - 1 of the remaining points are joined to either both or neither of A and B.
5.  0 < a1 ≤ a2 ≤ a3 ≤ ... is an unbounded sequence of integers. Let bn = m if am is the first member of the sequence to equal or exceed n. Given that a19 = 85, what is the maximum possible value of a1 + a2 + ... + a19 + b1 + b2 + ... + b85?

To avoid possible copyright problems, I have changed the wording, but not the substance, of the problems.

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© John Scholes
jscholes@kalva.demon.co.uk
25 Aug 2002