Question

Considerando que Cn,3=2Cn,2, o valor de n é:

A)4
B)6
C)8
D)10
E)12

Answer 1

Cn,3=2Cn,2

n!/(n-3)!3!  = 2 * n!/(n-2)!2!

n!/(n-3)!3*2!  = 2 * n!/(n-2)(n-3)!*2!

n!/(n-3)!3*2!  = n!/(n-2)(n-3)!

n!/3*2!  = n!/(n-2)

1/3*2!  =1/(n-2)

n-2 = 6

n=8