Solutions of Indefinite Equation
∑i=1mxi=x1+x2+?+xm=n\sum_{i=1}^m{x_i}=x_1+x_2+\cdots+x_m=n∑i=1m?xi?=x1?+x2?+?+xm?=n
- Num of positive integer solutions: Cn?1m?1C^{m-1}_{n-1}Cn?1m?1?
- Num of nonnegative integer solutions: Cn+m?1m?1?C^{m-1}_{n+m-1}?Cn+m?1m?1??