Question

如图1,在平面直角坐标系中,二次函数y=ax2+bx+c（a＞0）的图象顶点为D,与y轴交于点C,与x轴交于点A、B,点

Answer 1

y(0) = c = -3

y(3) = 9a+3b - 3 = 0

AO/OC = 1/3, A(-1,0)

y(-1) = a-b-3 = 0

a = b+3

9(b+3)+3b-3 = 0

b = -2

y = x^2 -2x - 3

D(2,-3)

设M坐标为(x,0)

tanMND = tan(180-MNA) =-12/5

要求角BMD=MND

tan BMD = -tanAMD = (x-1)/3 = 12/5

x = 41/5 > B点x 坐标

所以M不存在,T不存在