SOLUTION: You own 7 pairs of jeans and are taking 5 on vacation. In how many ways can you choose 5 pairs of jeans from the total group? Thanks for taking your time, and please don't just te

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Question 1066052: You own 7 pairs of jeans and are taking 5 on vacation. In how many ways can you choose 5 pairs of jeans from the total group?
Thanks for taking your time, and please don't just tell me the answer.
Answer by Boreal(15235) (Show Source):
You can put this solution on YOUR website!
It is 7C5 and that is 7!/5!2!. Notice that the two on the bottom add up to the number on the top (ignore the factorial part)
7!=7*6*5!=42 and 42/2 is 21.
5!2!= -- 5! 2!=2; the 5! cancel each other.
Any factorial can be stopped anywhere. n!=n*(n-1)!= n(n-1)(n-2)! and so forth.
Notice that 7C5 and 7C2 are the same.
0!=1. This comes from the exponential function, whose integral defines factorial functions. It is not an arbitrary designation.
There are 21 ways.