(1 ĐIỂM) CHO TỔNG S 1 .2C12018.20 2 .2C20182 .21 3 .2C2018...
Câu 7. (1 điểm) Cho tổng S 1 .
2
C
1
2018
.2
0
2 .
2
C
2018
2
.2
1
3 .
2
C
2018
3
.2
2
... 2018 .
2
C
2018
2018
.2
2017
2018.3 . 2.
a
2
1
2018
0
2
2018
2
1
2
2018
3
2
2
2018
2018
2017
a