9!/12!= 1/10*11*12;
(4!)^3/(3!)^2 = 4!*4*4;
4!= 24
4/10 = 2/5
4/12 = 1/3
24/3 = 8
8*2/5*1/11 = 16/55
其实不大,耐心拆拆就拆开了.
概率论问题,这个怎么算?我知道阶层是一直乘下去,但是数字太大怎么算?有没有公式?
9!/12!= 1/10*11*12;
(4!)^3/(3!)^2 = 4!*4*4;
4!= 24
4/10 = 2/5
4/12 = 1/3
24/3 = 8
8*2/5*1/11 = 16/55
其实不大,耐心拆拆就拆开了.