(x^m/x^2n)^3/x^(m-n)
=[x^(m-2n)]³/x^(m-n)
=x^(3m-6n)/x^(m-n)
=x^[(3m-6n)-(m-n)]
=x^(2m-5n)
∵(x^m/x^2n)^3/x^m-n与4x^2是同类项
∴x的指数相等即2m-5n=2 ①
又2m+5n=6 ②
①②得：m=2,n=2/5
∴4m^2-2n^2
=4×4-2×4/25
=16-8/25
=392/25简略点行吗？看不懂简略你更看不懂哪里不懂具体追问