求条件分式的值是分式化简、计算的重要内容,解题主要有以下三个方面: 一、将条件式变形后代入求值例1已知x/2=y/3=z/4,求x+2y-z/2x-y+z的值. 解:设x/2=y/3=z/4=k, 则x=2k,y=3k,z=4k. 原式说明:已知连比,常设比值k为参数,这种解题方法叫参数法. 例2 已知a2+ab-6b2=0,求a-b/a+b的 The value of the conditional fraction is an important part of fractional simplification and calculation. There are mainly three aspects to solve the problem: First, the conditional variant is substituted into the evaluation. Example 1 is known as x/2=y/3=z/ 4. Find the value of x+2y-z/2x-y+z. Solution: Let x/2=y/3=z/4=k, then x=2k,y=3k,z=4k. : Known ratio, the constant ratio k is a parameter, this method of solving the problem is called parameter method. Example 2 Knowing that a2+ab-6b2=0, find ab/a+b