C(42,4)/C(49,4)=?
C(42,4)/C(49,4)=?
日期:2021-10-28 11:44:33 人气:1
42X41X40X39 4!
___________ x____________
4! 49x48x47x46
7995
=___________
15134
___________ x____________
4! 49x48x47x46
7995
=___________
15134