### Formulas and Results of Permutations Combinations and Binomial Theorem

1. Factorial of is defined as , where is natural number. 2. (Permutation) 3. (Combination) 4. 5. 6. 7. 8. For large , is called Striling Approximation Formula. 9. 10. , , , 11. , 12. If is positive integer, then 13. 14. General Term 15. If is not positive integer, then the binomial expansion […]