y=(k+1)x^2-2(k-1)x+3(k-1)的图像的顶点在x轴上
则,顶点的纵坐标=0
12(k+1)(k-1)-4(k-1)²=0
(k-1)(3k+3-k+1)=0
(k-1)(2k+4)=0
2(k-1)(k+2)=0
k=1或k=-2