This is the fourth book of Math Contest Books Series. The book introduces the ways to use Cauchy's Inequalities to solve a variety of math contest problems. The book can be used by students preparing for math competitions such as AMC 10/12, ARML, AIME, and USAMO. Each chapter consists of (1) basic skill and knowledge section with examples, (2) exercise problems, and (3) detailed solutions to all problems. First book of Math Contest Books Series. The Mass Points Method: https: //www.amazon.com/Mass-Points-Method-Yongcheng-Chen/dp/1523265884 9th book: Problem Solving Using Auxiliary Lineshttps: //www.amazon.com/dp/1975681754 10th book: https: //www.amazon.com/Problem-Solving-Using-Vietas-Theorem/dp/1542800056