1.对称轴x=-b/2a=0,得:a=3
2.顶点的纵坐标=0,即:(4ac-b^2)/4a=0,则:4a-(a-3)^2=0,
a^2-10a+9=0,得:a=1或a=9
3.即方程:x^2-6x+c=0有两个根,b^2-4ac>0,36-4c>0,
c
1.对称轴x=-b/2a=0,得:a=3
2.顶点的纵坐标=0,即:(4ac-b^2)/4a=0,则:4a-(a-3)^2=0,
a^2-10a+9=0,得:a=1或a=9
3.即方程:x^2-6x+c=0有两个根,b^2-4ac>0,36-4c>0,
c