x→1时,1/（1-x）-3/（1-x^3）为什么等于-1

*-----------------------------------------------*| 6 4 X | 8 X X | X X 5 || X X X | X X X | X 7 8 || X X X | X X X | X X X ||---------------+---------------+--------------- || X X X | X X X | 5 1 X || X X X | X 6 X | X X X || 8 X X | 3 5 X | 2 X X || lim（ x→∞）（1+x / x)^3x [x（x+1）+x平方（x-1)]+（-3x) 填九宫格帮帮忙.x x 6 x x 7 x x 98 x x x 3 x 1 x x 9 x x 6 x 5 x 3 x x x 3 x x x x 1 8x x x 9 x 1 x x x2 1 x x x x 6 x x x 6 x 7 x 3 x x 1 x x 9 x 2 x x x 47 x x 8 x x 5 x x 七年级下册政治复习提纲(山东人民出版社)第五单元是 青春的脚步 青春的气息别弄错了啊!格式：X X X X X X X X X 1、X X X X X X X X X X.2、X X X X X X X X X.3、X X X X X X X X X X X. 解九宫格题目（X为未知数）9 X 2 X 7 X 8 X XX X 4 X X 9 X 6 X1 3 X 5 X X X X 24 X X 8 5 X X 1 XX 8 9 4 X 1 6 7 XX 1 X X 3 6 X X 88 X X X X 2 X 3 6X 5 X 6 X X 9 X XX X 7 X 4 X 2 X 1 请问这道题咋做 ：（x）X (x+1) X (x+2) X (x+3) =360 x/x+(1-x)/x-1/x /X-3/-/X-1/ (3x/x-1) x-3(x-1) | X+1 |>| X-3 | x+3/x-1 (x +1)(x-3) (x+3)(x-1) |x+1|-|x-3| (x+1)(x-3) lim √（3-x）-√（1+x）/x平方+x-2x→1