Function problem

[Miki]

Hello, I am new here and I pleased for help.. Questiom is: If X={1,2,3,4,5} how many funcion f:X-->X, which are bijection function are there?
Answer: A-1 B-5 C-26 D-16 E-120
Correct answer is C can someone please explain me this?

 

[pka]

Hello, I am new here and I pleased for help.. Questiom is: If X={1,2,3,4,5} how many funcion f:X-->X, which are bijection function are there?
Answer: A-1 B-5 C-26 D-16 E-120
Correct answer is C can someone please explain me this?

First, the answer is not C.
A bijection is a one-to-one function. For such a function on set to itself is a simple permutation.
Thus the answer here is \(\displaystyle \large 5!=120\)

 

[Otis]

... A-1 B-5 C-26 D-16 E-120

For future reference, please do not type hyphens in front of numbers, unless you're showing negative signs.

The multiple choices above are:

A) 1
B) 5
C) 26
D) 16
E) 120

?