由已知可得,解析式为：y = a(x-1) + 16 设A(x1,0) B(x2,0) 且x1＞x2,则：(x1 + x2)/2 = 1 点(x= 1,0) 是A、B的中点 x1 - x2 = 8 解得：x1 = 5,x2 = -3 把点A(5,0)代入y = a(x-1) + 16得：0 = a(5-1) +16,a = - 1 所以,y = - (x-1) + 16 化为一般形式：y = - x + 2x +15