对于各级数学竞赛中一类分式型不等式,将其分母换元,然后用新元素表示各个量,将复杂问题转化为已知的或简单的问题进行解决,达到事半功倍的目的,现举例说明,以飨读者.例1已知a、b、c∈R+,求证:a/(b+c)+b/(c+a)+c/(a+b)≥3/2(第26届莫斯科数学奥林匹克试题) For a class of fractional inequalities at all levels of mathematics competition, the denominator for the yuan, and then use the new elements that the amount of the complex problems into known or simple problems to solve, to achieve a multiplier purpose, an example , To 飨 readers. Example 1 Known a, b, c ∈ R +, verify: a / b + c + b / c + a + c / a + b ≥ 3/2 (26th Moscow Mathematical Olympiad)