olymmath

DK-GEORGMOHR 1998

Georg Mohr Contest 1998.

Official paper

The official paper in 1 language

Danish

Other problems

Problem 2

For any real number mm , the equation x2+(m−2)x−(m+3)=0x^2+(m-2)x- (m+3)=0 has two solutions, denoted x1x_1 and x2x_2 . Determine mm such that x12+x22x_1^2+x_2^2 is the minimum possible.

Problem 4

Let aa and bb be positive real numbers with a+b=1a + b =1 . Show that (a+1a)2+(b+1b)2≥252.\left(a+\frac{1}{a}\right)^2 + \left(b+\frac{1}{b}\right)^2 \ge \frac{25}{2}.

Problem 5

A neat fruit arrangement on a large round dish is edged with strawberries. Between 100100 and 200200 berries are used for this border. A deliciously hungry child eats first one of the strawberries and then starts going round and round the dish, she eats strawberries in the following way: When she has eaten a berry, she leaves it next lie, then she eats the next, leaves the next, etc. Thus she continues until there is only one strawberry left. This berry is the one that was lying right after the very first thing she ate. How many berries were there originally?