an=a1⋅qn−1,公比 q=0;等比中项看下标积。
We consider now a problem called the Monty Hall problem. This has long been a favorite problem but was revived by a l…
一位被吉尼斯纪录认证为全世界最聪明的女人,因为说了一句"该换门",收到了一万封信,其中一千多封署名为博士。这道题让她顶了三年的骂。