(m+n)^2+4m+4n+4m^2
=5m^2+(4+2n)m+(n^2+4n)
令5m^2+(4+2n)m+(n^2+4n)＝0
△＝（4＋2n）^2-4*5*（n^2+4n）= -16n^2-64n+16
m= [-(4+2n)±√△]/10
所以
(m+n)^2+4m+4n+4m^2
＝5（m＋（（n＋2＋2√(-n^2-4n+1))/5）*（m＋（（n＋2）－2√(-n^2-4n+1))/5)