Asked by chandice
can soemone tells me what this means
10!
----- =45
2!*8!
i don't get the explnation points or how they got 45 out of that
10!
----- =45
2!*8!
i don't get the explnation points or how they got 45 out of that
Answers
Answered by
Reiny
It is the formula for "combinations"
In this case it could mean:
There are 10 people that all shake hands with each other. How many handshakes are there?
or
given 10 different elements, how many subsets can be found that contain 2 elements?
8! means 1x2x3x4x5x6x7x8 = 40320
Several notations are used
C(n,r) = <sub>n</sub>C<sub>r</sub>
= n!/(r!(n-r)!)
so C(10,2) = 10!/(2!8!)
= 3628800/(2*40320) = 45
In this case it could mean:
There are 10 people that all shake hands with each other. How many handshakes are there?
or
given 10 different elements, how many subsets can be found that contain 2 elements?
8! means 1x2x3x4x5x6x7x8 = 40320
Several notations are used
C(n,r) = <sub>n</sub>C<sub>r</sub>
= n!/(r!(n-r)!)
so C(10,2) = 10!/(2!8!)
= 3628800/(2*40320) = 45
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