5ac/10a²b³c 4bc/10a²b³c通分：3c／2ab²和﹣a／8bc²;﹙4﹚1／y－1和1／y＋1,麻烦，谢谢！12c³/8ab²c²-a²b/8ab²c²(y+1)/[(y+1)(y-1)] (y-1)/[(y+1)(y-1)]