有题意有A(x1,0)、B(x2,0),(x1<0<x2) 所以OA=-x1 OB=x2抛物线开口向上 与y轴交于C 所以OC=-(k+1)(OA+OB)²=OC²+16所以(x2-x1)^2=(k+1)^2+16x1+x2=-(k+0.5)/0.5 x1x2=(k+1)/0.5 ( 根与系数关系)(x2-x1)^2=(k+1)^2+16(x1+x2)^2-4x1x2=(k+1)^2+164(k+0.5)^2-4X2X(k+1)=(k+1)^2+16