A:① ④
B:② ④
C:③ ④
D:① ②
Mr father this watch in 2006. He it for 10 years.
已知抛物线y=x2+bx+c经过A(﹣1,0),B(3,0)两点,与y轴相交于点C,该抛物线的顶点为点D