设集合S={1,2,3,4,5,6,7,8,9},集合A={a1,a2,a3}是
题型:选择题
问题:
设集合S={1,2,3,4,5,6,7,8,9},集合A={a1,a2,a3}是S的子集,且a1,a2,a3满足a1<a2<a3,a3-a2≤6,那么满足条件的集合A的个数为( )
A.78
B.76
C.84
D.83
设集合S={1,2,3,4,5,6,7,8,9},集合A={a1,a2,a3}是S的子集,且a1,a2,a3满足a1<a2<a3,a3-a2≤6,那么满足条件的集合A的个数为( )
A.78
B.76
C.84
D.83