With 1, Without 2 and 3
Difficulty: Easy · Topics: Discrete Mathematics, Permutations
A=\1,2,3,4,5,6,7\
In how many of the 3-element permutations of A does 1 appear while 2 and 3 do not?
Difficulty: Easy · Topics: Discrete Mathematics, Permutations
A=\1,2,3,4,5,6,7\
In how many of the 3-element permutations of A does 1 appear while 2 and 3 do not?