数学题:sqrt(81*82*83*84+1)

sqrt(81*82*83*84+1)
=sqrt[(82*83)*(81*84)+1]
=sqrt[6806*6804+1]
=sqrt[(6804+2)*6804+1]
=sqrt[6804*6804+2*6804*1+1]
=sqrt[(6804+1)*(6804+1)]
=6805

6805

n!=n*(n-1)!
n的阶乘的展开形式为:
n!=m*(n-1)*(n-2)*(n-3)……2*1
零的阶乘规定等于1,即
0!=1
例f9_3.C
#include
long int fact();/*声明被调用函数返回值为长整型)*/
main()