Question

Tính nhanh  1/3+1/6+ 1/10 + 1/15+ .....+1/4950

Answer 1

1/3+1/6+1/10+1/15+......+1/4950

=2x（1/6+1/12+1/20+1/30+……+1/9900）

=2x（1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+……+1/99-1/100）

=2x（1/2-1/100）

=1-1/50

=49/50

**** nhé

Answer 2

Đáp án là 49/50 nha hatsune miku 

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