$x_1 + x_2 + x_3 + x_4 = 28$
I tried to solve it with generating functions.
Is it correct to get to the form of
${(1 + x + {x^2} + {x^3} + ....)^4}$
and this equals to:
${(1 - x)^{ - 4}}$
and then solve it with binomial expansion ?
Is this correct ?
every question similar to "how many solutions are axsist to this equation?"
can be solved this method?
I know there're a lot of methods and manipulations for this kind of problem.
Can you confirm it's the right path for this kind of problems?
It's like distribute 28 things into 4 objects.
This is why I used generating functions.
