olymmath

MN-MO 2001

Mongolian Mathematical Olympiad 2001.

Other problems

Problem 1

Suppose that a sequence x1,x2,…,x2001x_1,x_2,\ldots,x_{2001} of positive real numbers satisfies 3xn+12=7xnxn+1−3xn+1−2xn2+xn and x37=x2001.3x^2_{n+1}=7x_nx_{n+1}-3x_{n+1}-2x^2_n+x_n\enspace\text{ and }\enspace x_{37}=x_{2001}. Find the maximum possible value of x1x_1 .

Problem 2

In an acute-angled triangle ABCABC , a,b,ca,b,c are sides, ma,mb,mcm_a,m_b,m_c the corresponding medians, RR the circumradius and rr the inradius. Prove the inequality a2+b2a+b⋅b2+c2b+c⋅a2+c2a+c≥16R2rmaa⋅mbb⋅mcc.\frac{a^2+b^2}{a+b}\cdot\frac{b^2+c^2}{b+c}\cdot\frac{a^2+c^2}{a+c}\ge16R^2r\frac{m_a}a\cdot\frac{m_b}b\cdot\frac{m_c}c.