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含有多元变量(含两个或两个以上变量)的问题,是最近几年各地高考及模拟试卷中常见的一类试题,此类问题知识覆盖面广,综合性强,灵活多变,对学生的思维要求较高,成了教师教学及学生学习中的难点.本文意在通过一道简单的例题,给出实战中常见的四种解题策略.问题若正数a,b满足ab=a+b+3,则z=a+b的取值范围是.策略一消元:即将b表示成关于a的函数,或反之.此类
The problem of having multiple variables (including two or more variables) is a common type of examination questions in college entrance examination and simulation papers all over the country in recent years. Such problems have wide range of knowledge, strong comprehensiveness and flexibility, Thinking is more demanding, has become a difficult teaching and student learning.This paper is intended to give a common example of four solution strategies in a practical case through a simple example.If the positive a, b satisfy ab = a + b +3, then z = a + b has a value range of 1. Strategy One elimination: Let b be a function of a, or vice versa.