若(x^m/x^2n)^3/x^m-n与4x^2为同类项,且2m+5n=7,求4m^2-25n^2的值

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若(x^m/x^2n)^3/x^m-n与4x^2为同类项,且2m+5n=7,求4m^2-25n^2的值
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若(x^m/x^2n)^3/x^m-n与4x^2为同类项,且2m+5n=7,求4m^2-25n^2的值
若(x^m/x^2n)^3/x^m-n与4x^2为同类项,且2m+5n=7,求4m^2-25n^2的值

若(x^m/x^2n)^3/x^m-n与4x^2为同类项,且2m+5n=7,求4m^2-25n^2的值
(x^m/x^2n)^3*x^(m-n)
=[x^(m-2n)]^3/x^(m-n)
=x^(3m-6n)/x^(m-n)
=x^(2m-5n)
x^(2m-5n)与4x^2为同类项
所以2m-5n=2,2m+5n=7
(2m-5n)(2m+5n)=4m^2-25n^2=14