gwd-24-4滔滔

lovetiky

the method 2 should be C(6,1)*C(2,1)/C(8,2)+C(2,2)/C(8,2)

noticing that C(8,2)=8*7/2, you will get the answer after calculating the expression.

[此贴子已经被作者于2006-7-9 10:40:16编辑过]

lovetiky

something careless， already corrected