So Sánh dãy số
Cho S = 1+2+2^2+2^3+....+2^9 . Hãy so sánh S với 5 x 2^8
Tacó:
2S=2.(1+2+22+23+…..+29)=2+22+23+24+…+210.
=>2S-S=210-1
=>S=210-1.
5.28=(4+1).28=22.28+28=210+28.
Vậy S<5.28.
![](http://www.blogger.com/img/icon18_email.gif)
![](http://img2.blogblog.com/img/icon18_edit_allbkg.gif)
Subscribe to:
Post Comments (Atom)
Cho S = 1+2+2^2+2^3+....+2^9 . Hãy so sánh S với 5 x 2^8
Tacó:
2S=2.(1+2+22+23+…..+29)=2+22+23+24+…+210.
=>2S-S=210-1
=>S=210-1.
5.28=(4+1).28=22.28+28=210+28.
Vậy S<5.28.
© 2012 Học Để ThiBlog tài liệu
No comments: