Difference between revisions of "1975 IMO Problems"
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Revision as of 11:37, 24 November 2010
Problems of the 17th IMO 1975 in Bulgaria.
Problem 1
Let be real numbers such that Prove that, if is any permutation of , then
Problem 2
Let be an infinite increasing sequence of positive integers. Prove that for every there are infinitely many which can be written in the form with positive integers and .
Problem 3
On the sides of an arbitrary triangle , triangles are constructed externally with . Prove that and .
Problem 4
When is written in decimal notation, the sum of its digits is . Let be the sum of the digits of . Find the sum of the digits of . ( and are written in decimal notation.)
Problem 5
Determine, with proof, whether or not one can find 1975 points on the circumference of a circle with unit radius such that the distance between any two of them is a rational number.
Problem 6
Find all polynomials , in two variables, with the following properties:
(i) for a positive integer and all real (that is, is homogeneous of degree ),
(ii) for all real
(iii)