tailieunhanh - ĐỀ THI TOÁN APMO (CHÂU Á THÁI BÌNH DƯƠNG)_ĐỀ 24

Tham khảo tài liệu 'đề thi toán apmo (châu á thái bình dương)_đề 24', khoa học tự nhiên, toán học phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 40th United States of America Mathematical Olympiad Day II 12 30 PM - 5 PM EDT April 28 2011 USAMO 4. Consider the assertion that for each positive integer n 2 the remainder upon dividing 22 by 2 1 is a power of 4. Either prove the assertion or hnd with proof a counterexample. USAMO 5. Let P be a given point inside quadrilateral ABCD. Points Q1 and Q2 are located within ABCD such that Q1BC ABP Q1CB DCP Q2AD BAP Q2DA CDP. Prove that Q1Q2 II AB if and only if Q1Q2 II CD. USAMO 6. Let A be a set with A 225 meaning that A has 225 elements. Suppose further that there are eleven subsets A1 . A11 of A such that Aj 45 for 1 i 11 and ịAi n Aj 9 for 1 i j 11. Prove that A1 u A2 u u A11 165 and give an example for which equality holds. Copyright Committee on the American Mathematics Competitions Mathematical Association of .

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