• 2021-04-14
    设集合有3个元素,则上的等价关系的个数为。https://img-ph-mirror.nosdn.127.net/4QRI30JkP7V6jj57tHynuQ==/6608641027026760798.pnghttps://img-ph-mirror.nosdn.127.net/4QRI30JkP7V6jj57tHynuQ==/6608641027026760798.png