x2+y2-2(m+3)+2(1-4m2)y+16m4+9=0是一个圆,求半径r取值范围

[x-(m+3)]^2+[y+(1-4m^2)]^2=-16m^4-9+(m+3)^2+(1-4m^2)^2所以r^2=-16m^4-9+(x+3)^2+(1-4m^2)^2>0-16m^4-9+(m+3)^2+(1-4m^2)^2=-16m^4-9+m^2+6m+9+16m^4-8m^2+1=-7m^2+6m+1>07m^2-6m-1