Turkish NMO First Round - 2000 P-30 (Number Theory)
Source:
July 8, 2012
Problem Statement
How many ordered integer pairs (x,y) (0≤x,y<31) are there satisfying (x2−18)2≡y2(mod31)?<spanclass=′latex−bold′>(A)</span>59<spanclass=′latex−bold′>(B)</span>60<spanclass=′latex−bold′>(C)</span>61<spanclass=′latex−bold′>(D)</span>62<spanclass=′latex−bold′>(E)</span>None