Permutations with Repetition and Repeated Elements

[Big-Daddy]

The theory says that if you have x objects containing a repeats of one element and b repeats of another, N_p(without repetition)=x!/(a!b!).

If you have x objects and repetitions are allowed, N_p(with repetition)=x^x, correct?

Combining these, if we have x objects containing a repeats of one element and b repeats of another, and repetitions are allowed, N_p(with repetition)=x^x/(a!b!). Is this right?

 

[fresh_42]

I get dizzy each time again and again. Better to look it up:
https://en.wikipedia.org/wiki/List_of_permutation_topics
or if you don't mind the language or use chrome which translates it for me:
https://de.wikibooks.org/wiki/Formelsammlung_Mathematik:_Elementare_Kombinatorik