S 1 2C  1N2 C2 2N 2 C3 3N

222. - TN TO HOP XAC SUAT DAP AN CHI TIET
TN TO HOP XAC SUAT DAP AN CHI TIET
222. Tính tổng:

S 1 2C

 

1

n

2 C

2

2

n

2 C

3

3

n

... ( 1) 2 C

 

n n

n

n

a/

1

n

b/

( 2)

n

c/

( 3)

n

d/

( 1)

n