TT2 math14

XIAOXIANGXI

Q14:

C_(m,n) = m! / [(m-n)! n!] for nonnegative integers m and n, m ³ n.  If C_(5,3) = C_(5,x) and x ¹ 3, what is the value of x?

 A.     0

 A.     0

B.     1

C.     2

D.     4

E.      5

Answer: c

不明白啥意思啊？没找到讨论贴

wujie_rens

C(m,n)=m!/[(m-n)!n!]

C(5,3)=5!/[(5-3)!3!]=5!/[(2)!3!]

=C(5,2)=5!/[(5-2)!2!]=5!/[(3)!2!]