In China, lots of excellent maths students take an active interest in
various maths contests and the best six senior high school students will
be selected to form the IMO National Team to compete in the
International Mathematical Olympiad. In the past ten years China's IMO
Team has achieved outstanding results -- they won the first place almost
every year.The authors are coaches of China's IMO National Team, whose
students have won many gold medals many times in IMO.This book is part
of the Mathematical Olympiad Series which discusses several aspects
related to maths contests, such as algebra, number theory,
combinatorics, graph theory and geometry. The book explains many basic
techniques for proving inequalities such as direct comparison, method of
magnifying and reducing, substitution method, construction method, and
so on.