=1/(x-2)(x-1)+1/(x-2)(x-3)+1/(x-3)(x-4)-4/(x-1)(x-5) 帮你删除了 1/x2-7
=1/(x-2)-1/(x-1)+1/(x-3)-1/(x-2)+1/(x-4)-1/(x-3)-[1/(x-5)-1/(x-1)]
=1/(x-5)不对啊，为什么要把1/x2-7删掉？你那个多写了你仔细看一下我打错了，sorry，原题是1/x2-3x+2+1/x2-5x+6+1/x2-7x+12+1/x2-9x+20-4/x2-6x+5再解一次好吗？！上面我给你的答案就是这个的解不对，题目不一样了，别人说正确答案是0，好吗？题目不一样了哦你里面还有一个1/x2-9x+20我加上去，刚才我本来少写了一项 =1/(x-2)(x-1)+1/(x-2)(x-3)+1/(x-3)(x-4)+1(x-4)(x-5)-4/(x-1)(x-5) =1/(x-2)-1/(x-1)+1/(x-3)-1/(x-2)+1/(x-4)-1/(x-3)+1/(x-5)-1/(x-4)-[1/(x-5)-1/(x-1)] 第一项和第四项抵消第二项和最后一项抵消 =0