数学问题，算道题

(2m-3n)^2*(2m+3n)^2
=[(2m-3n)*(2m+3n)]^2
=[4m^2-9n^2]^2
=16m^4-72m^2*n^2+81n^4

(2m-3n)^2*(2m+3n)^2
=[(2m-3n)*(2m+3n)]^2
=(4*m^2-9*n^2)^2
=16*m^4-72*m^2*n^2+81*n^4

答案是(4m^2-9n^2)^2=16m^4-72m^2*n^2+81n^4

是化简吗？
根据m^2-n^2=(m-n)(m=n)
所以原式=(2m-3n)(2m+3n)(2m-3n)(2m+3n)
=(4m^2-9n^2)^2
=16m^4-72m^2n^2+81n^4

(2m-3n)^2*(2m+3n)^2
=[(2m-3n)*(2m+3n)]^2
=(4*m^2-9*n^2)^2
=16*m^4-72*m^2*n^2+81*n^4

(2m-3n)^2*(2m+3n)^2
=[(2m-3n)*(2m+3n)]^2
=[4m^2-9n^2]^2
=16m^4-72m^2*n^2+81n^4