Question

如图,在平面直角坐标系中,抛物线y=ax2+bx+c(ac不等于0)与x轴交于点A与点B(点A在B的左侧),与y轴交于点

Answer 1

(1)

y = 2x² + 5x/2 + 1/2 = (x + 1)(2x + 1/2)

x = -1, x = -1/4

OA = 1, OB =1/4, OC = 1/2OA*OB = 1/4 = OC²是黄金抛物线

(2)

(3)见(1), c= -1/3时,抛物线是由c = 1/3平移得到的:

y = 3x² + 5x − 1╱3 = 3(x + 5╱6)² − 7/4y = 3x² + 5x - 1╱3 = 3(x + 5╱6)² − 29/12后者是前者向下平移2/3得打的