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nguyễn ngọc thiên  thanh
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Nguyễn Nam Cao
6 tháng 7 2015 lúc 7:32

\(A=\frac{2013}{2014}+\frac{2014}{2015}+\frac{2015}{2013}=3,00000074\)

Vì 3,00000074 > 3 nên A > 3

Lê Xuân Đạt
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Trần Thị Loan
7 tháng 5 2015 lúc 19:59

\(A=\frac{2013}{2014}+\frac{2014}{2015}+\frac{2013}{2013}+\frac{1}{2013}+\frac{1}{2013}=\left(\frac{2013}{2014}+\frac{1}{2013}\right)+\left(\frac{2014}{2015}+\frac{1}{2013}\right)+1\)

Ta có: \(\frac{2013}{2014}+\frac{1}{2013}>\frac{2013}{2014}+\frac{1}{2014}=\frac{2014}{2014}=1\)

\(\frac{2014}{2015}+\frac{1}{2013}>\frac{2014}{2015}+\frac{1}{2015}=\frac{2015}{2015}=1\)

=> A > 1+ 1 + 1 = 3

cao trung hieu
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Trần Đức Thắng
14 tháng 8 2015 lúc 18:30

a = \(\frac{2013}{2014}+\frac{2014}{2015}=\frac{2014-1}{2014}+\frac{2015-1}{2015}\)

  \(=1-\frac{1}{2014}+1-\frac{1}{2015}\)

   \(=2-\left(\frac{1}{2014}+\frac{1}{2015}\right)>1\) (1)

b =  \(\frac{2013+2014}{2014+2015}

nam nguyen hoai
5 tháng 3 2018 lúc 19:02

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h

Dark Wings
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Phương An
1 tháng 9 2016 lúc 12:09

A = (n + 2015)(n + 2016) + n2 + n

(n + 2015)(n + 2015 + 1) + n(n + 1)

Tích 2 số tự nhiên liên tiếp luôn chia hết cho 2

=> (n + 2015)(n + 2015 + 1) chia hết cho 2

      n(n + 1) chia hết cho 2

=> (n + 2015)(n + 2015 + 1) + n(n + 1) chia hết cho 2

=> A chia hết cho 2 với mọi n \(\in\) N (đpcm)

beelzebub
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Lâm liên quân
13 tháng 4 2017 lúc 17:27

a)\(\frac{2013}{2015}< \frac{2014}{2016}\)

b)\(\frac{2013+2014}{2014+2015}< \frac{2013}{2014}+\frac{2014}{2015}\)

stubasa10
14 tháng 4 2019 lúc 20:36

ta có tính chất \(\frac{a}{b}\)>1 suy ra \(\frac{a.m}{b.m}\).........

phạm thị oanh
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Đinh Tuấn Việt
7 tháng 5 2015 lúc 20:37

http://olm.vn/hỏi-đáp/question/85092.html, bạn ấn vào đây có bài y chang luôn !

Lê Yến Nhi
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Trần Hữu Thắng
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Nguyễn Dăng Chung
3 tháng 3 2016 lúc 9:39

de ot la dau = nha

kokomy
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Cute phômaique
6 tháng 5 2015 lúc 9:45

Ta có: \(\frac{2013}{2014}>\frac{2013}{2014+2015}\) (1)
\(\frac{2014}{2015}>\frac{2014}{2014+2015}\) (2)
ộng caác bất đẳng thứa (1) và (2) vào vế với vế:
\(\frac{2013}{2014}+\frac{2014}{2015}>\frac{2013+2014}{2014+2015}\Rightarrow A>B\)

kokomy
6 tháng 5 2015 lúc 9:55

cảm ơn các bạn                         

Toán-LÍ-Hoá (Hội Con 🐄)...
13 tháng 11 2016 lúc 13:51

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