MathDB

8

Part of 2009 National Olympiad First Round

Problems(1)

two elements whose sum is a perfect square

Source: 0

4/28/2009
S \equal{} \{1,2,\dots,n\} is divided into two subsets. How the set is divided, if there exist two elements whose sum is a perfect square, then n n is at least ?
<spanclass=′latex−bold′>(A)</span> 13<spanclass=′latex−bold′>(B)</span> 14<spanclass=′latex−bold′>(C)</span> 15<spanclass=′latex−bold′>(D)</span> 16<spanclass=′latex−bold′>(E)</span> 17<span class='latex-bold'>(A)</span>\ 13 \qquad<span class='latex-bold'>(B)</span>\ 14 \qquad<span class='latex-bold'>(C)</span>\ 15 \qquad<span class='latex-bold'>(D)</span>\ 16 \qquad<span class='latex-bold'>(E)</span>\ 17