x^2-（2m+4）x+m^2-4=0x^2-2(m+2)x+(m+2)(m-2)=0x^2-2(m+2)x+(m+2)^2=(m+2)^2-(m^2-4)=4m+8[x-(m+2)]^2=4(m+2)(1):m+2>=0===>m>=-2x-(m+2)=+/-2根号(m+2)x1=m+2+2根号(m+2)x2=m+2-2根号(m+2)(2):m+2m