So today in my lecture my prof went over this property of the binomial theorem when dealing with combination problems that allow repetitions
The number of nonnegative integer solutions of the equation: $x_1 + x_2 + · · · + x_n = r$ where you can use $\binom{n+r-1}{r}$
I was wondering, can I use this to determine the number of integer solutions to a system of equations?
thanks!
