(x^m÷x^2n)^3÷x^(m-n)=x^(2m-5n).由于上式与4x^2是同类项,则2m-5n=2;----------------(1)又: 2m+5n=6.---------------------------------------------(2)两个式子相加得：4m=8,m=2.把m=2代入2m-5n=2,可求得n=2/5...