m^2十n^2十4m一2n十5=o,求3m^2十5n^2一4

(m^2十4m+2）^2一4=(m^2十4m+2）^2一2^2
=[(m^2十4m+2）+2][(m^2十4m+2）-2]
=(m^2十4m+4)(m^2十4m)
=m(m+2)^2(m+4)