m^2-n^2+3m-3n＝0(m+n)(m-n)-3(m-n)=0(m-n)(m+n-3)=0m-n=0或m+n-3=0（m^3n-2m^2n^2+mn^3)/(2mn)+2mn=（m^3n-2m^2n^2+mn^3+4m^2n^2)/(2mn)=（m^3n+2m^2n^2+mn^3)/(2mn)=mn(m+n)^2/2mn=(m+n)^2/2若m-n=0,则m=n原式=2m^...