{5，-8，11，-14，17，-20，23}的真子集列举
1、集合A为7个元素，列举该集合的全部子集。
2、含1个元素的子集，此时有7个子集，具体如下：
A3={5}，A4={-8}，A5={11};
A6={-14}，A7={17}，A8={-20};
A9={23}；
3、有2个元素的子集情况，此时个数为C(7,2)=21个，
A10={5,-8}，A11={5,11}，A12={5,-14};
A13={5,17}，A14={5,-20}，A15={5,23};
A16={-8,11}，A17={-8,-14}，A18={-8,17};
A19={-8,-20}，A20={-8,23}，A21={11,-14};
A22={11,17}，A23={11,-20}，A24={11,23};
A25={-14,17}，A26={-14,-20}，A27={-14,23};
A28={17,-20}，A29={17,23}，A30={-20,23};
4、此时个数为C(7,3)=35个，列举如下：
A31={5,-8,11}，A32={5,-8,-14}，A33={5,-8,17};
A34={5,-8,-20}，A35={5,-8,23}，A36={5,11,-14};
A37={5,11,17}，A38={5,11,-20}，A39={5,11,23};
A40={5,-14,17}，A41={5,-14,-20}，A42={5,-14,23};
A43={5,17,-20}，A44={5,17,23}，A45={5,-20,23};
A46={-8,11,-14}，A47={-8,11,17}，A48={-8,11,-20};
A49={-8,11,23}，A50={-8,-14,17}，A51={-8,-14,-20};
A52={-8,-14,23}，A53={-8,17,-20}，A54={-8,17,23};
A55={-8,-20,23}，A56={11,-14,17}，A57={11,-14,-20};
A58={11,-14,23}，A59={11,17,-20}，A60={11,17,23};
A61={11,-20,23}，A62={-14,17,-20}，A63={-14,17,23};
A64={-14,-20,23}, A65={17,-20,23};
5
6、※.有4个元素的子集情况
此时个数为C(7,4)=C(7,3)=35个，列举如下：
A66={5,-8,11,-14}，A67={5,-8,11,17};
A68={5,-8,11,-20}, A69={5,-8,11,23};
A70={5,-8,-14,17}，A71={5,-8,-14,-20};
A72={5,-8,-14,23}，A73={5,-8,17,-20};
A74={5,-8,17,23}, A75={5,-8,-20,23};
A76={5,11,-14,17}, A77={5,11,-14,-20};
A78={5,11,-14,23}, A79={5,11,17,-20};
A80={5,11,17,23}, A81={5,11,-20,23};
A82={5,-14,17,-20}, A83={5,-14,17,23};
A84={5,-14,-20,23}, A85={5,17,-20,23};
A86={-8,11,-14,17}, A87={-8,11,-14,-20};
A88={-8,11,-14,23}, A89={-8,11,17,-20};
A90={-8,11,17,23}, A91={-8,11,-20,23};
A92={-8,-14,17,-20}, A93={-8,-14,17,23};
A94={-8,-14,-20,23}, A95={-8,17,-20,23};
A96={11,-14,17,-20}, A97={11,-14,17,23};
A98={11,-14,-20,23}, A99={11,17,-20,23};
A100={-14,17,-20,23};
7
8、※.有5个元素的子集情况
此时个数为C(7,5)=C(7,2)=21个，列举如下：
A101={5,-8,11,-14,17}, A102={5,-8,11,-14,-20};
A103={5,-8,11,-14,23}, A104={5,-8,11,17,-20};
A105={5,-8,11,17,23}, A106={5,-8,11,-20,23};
A107={5,-8,-14,17,-20}, A108={5,-8,-14,17,23};
A109={5,-8,-14,17,23}, A110={5,-8,17,-20,23};
9、A111={5,11,-14,17,-20}, A112={5,11,-14,17,23};
A113={5,11,-14,-20,23}, A114={5,11,17,-20,23};
A115={5,-14,17,-20,23}, A116={-8,11,-14,17,-20};
A117={-8,11,-14,17,23}, A118={-8,11,-14,-20,23};
A119={-8,11,17,-20,23}, A120={-8,-14,17,-20,23};
A121={11,-14,17,-20,23};
10、※.有6个元素的子集情况，此时个数为C(7,6)=C(7,1)=7个，列举如下：
A122={5,-8,11,-14,17,-20};
A123={5,-8,11,-14,17,23};
A124={5,-8,11,-14,-20,23};
A125={5,-8,11,17,-20,23};
A126={5,-8,-14,17,-20,23};
A127={5,11,-14,17,-20,23};
A128={-8,11,-14,17,-20,23}。
