Question

[Pham Trong Bach]

Tính nhanh:

a ) − 1 3 . − 1 5 . − 1 7 . − 1 9

b ) 1000 − 1 3 1000 − 2 3 1000 − 3 3 . ... 1000 − 60 3

c ) A = 1 1 .2 + 1 2 .3 + . ... + 1 99 .10

Answer 1

[Cao Minh Tâm]