若（x^m÷x^2n)^3÷x^m-n与-1/4x^2为同类项,求4m^2-2n^2 (+﹏+)~狂晕
问题描述：
若（x^m÷x^2n)^3÷x^m-n与-1/4x^2为同类项,求4m^2-2n^2 (+﹏+)~狂晕
答
（x^m÷x^2n)^3÷x^(m-n)=x^3(m-2n)÷x^(m-n)=x^(3m-6n-m+n)=x^(2m-5n)
与-1/4x^2为同类项
则2m-5n=2 2m=5n+2
4m^2-2n^2=(5n+2)^2-2n^2=23n^2-20n+4=23(n-10/23)^2-8/23
无法求最后结果,有最小值-8/23