sat
1、if18倍根号下18=r倍根号下t,whererandtarepositiveintegersandr>t,whichoffollowingcouldbethevalueofrt?答案为什么是108啊完全没有思路啊
2、ifthefivecards12345shownaboveareplacedinarowsothatnumber3isneverateitherend,howmanydifferentarrangementsarepossible?我混淆了排列组合一直很差怎么办啊到底怎么排列啊!