已知2m-3n/3m+n=2 求(4m-6n/9m+3n)+(18m+6n/4m-6n)的值.要有步骤和讲解.
问题描述：
已知2m-3n/3m+n=2 求(4m-6n/9m+3n)+(18m+6n/4m-6n)的值.要有步骤和讲解.
答
2m-3n/3m+n=2 ,则2m-3n=6m+2n 4m=-5n m=-5n/4 所以(4m-6n/9m+3n)+(18m+6n/4m-6n) =[(-5n-6n)/(3n-45n/4)]+(6n-45n/2)/(4m+15m/2) =4/3-33/23 =-7/69