解:由题意A、B在原点的右侧,且|x1?x2|= (x1+x2)2?4x1x2 = (k+1)2?4 ,∵△ABC为等边三角形,∴AB=CB,∴CD=CB?sin60°=AB?sin60°= 3 2 (k+1)2?4 ,又∵C点纵坐标为 4?(k+1)2 4 ,∴ 3 2 (k+1)2?4 =|1?( k+1 2 )2|,令(k+1)2=a,则原式可化为