已知二次函数y=ax2+bx+c的图象交x轴于A、B两点,交y轴于C点,且△ABC是直角三角形

y = (1/2)(x+1)(x - 4)
y = -(1/2)(x + 1)(x - 4)
y = (1/3)(x +3)(x - 3)
y = a(x - m)(x - n)中,a²mn = -1即可,能做出无穷个.