Page 69 - Fixtures

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ABC , ABD, ABE, ACD, ACE, ADE, BCD, BCE, BDE,CDE

.10

n r
0≤r ≤n
. Crn  n  C(n,r)
r

C(n,r) = n !
r !(n − r)!

C(n,r) P(n,r) )r

.(r !

.C(n,r) = P(n,r) = n ! . P(n,r) = r !C(n,r)

r ! r !(n − r)!

. r ≤ n C(n,r) = C(n,n − r)

.C(n,n − r) = n ! = n ! = C(n,r)

(n − r)![n − (n − r)]! (n − r)!r !

nr

.n n −r

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