Question

Please help! Permutations. Can someone help explain them? Please help! I have no idea what this is! It's very confusing! Thank you. :)

For the questions simplify the expression.

1. 9!
a. 45
b. 362,880
c. 265,456
d. 125,963

2. 25P3
a. 12,755
b. 14,290
c. 13,800
d. 18,250

Answer 1

k

Answer 2

this is example of how to open a factorial
4! = 4 × 3 × 2 × 1 = 24
now try to open the first one

Answer 3

9!=\[\prod_{i=1}^{9} i\]

Answer 4

Okay, so 9! = 9 x 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1 = 362,880 Am I right?

Answer 5

yes

Answer 6

yes

Answer 7

Okay, thanks! Now how would I solve the next one? :)

Answer 8

\[25P3=25C3*3!\]

Answer 9

\[25C3=25C22\]

Answer 10

so it is \[25C22*3!\]

Answer 11

\[25*24*23=13800\]

Answer 12

\[nCr=\frac{ n! }{ (n-r)!r! }\]

Answer 13

Oh, that makes so much sense now! Thank you! :)

Answer 14

Simply u can also find permutation by this formula nPr=n!/(n−r)!