Question

如图,已知抛物线Y=二分之一X方+bx+c与X轴相交于A(-4,0)和B（1,0）两点,与Y轴交于点C在抛物线对称轴上

Answer 1

y = 1/2 x^2 + bx + c = 1/2 (x+4)(x-1)

A(-4,0),B(1,0),C(0,-2)

对称轴x = -1.5,

M(-1.5, y)

MA-MC = 根号(2.5^2 + y^2) - 根号(1.5^2 + (y+2)^2)

y = -5时,M(-1.5,-5), MA-MC = 5