So sánh:
1. 212121/ 353535 và 131313/ 141414
2. 2012/ 2013+ 2013/ 2014+ 2015/ 2012 vs 3
K
Khách
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Những câu hỏi liên quan
KT
3
27 tháng 2 2016
1)Ta có : 212121/353535 = 212121:10101/353535:10101 = 21/35 = 3/5
131313/141414 = 131313:10101/141414:10101 = 13/14
Ta có : 3/5 = 42/70 ; 13/14 = 65/70
Vì 42<65 => 42/70<65/70 => 212121/353535<131313/141414
2)Ta có : 2012/2013<1
2013/2014<1
2014/2015<1
=> 2012/2013+ 2013/2014+ 2015/2012<1+1+1=3
Vậy 2012/2013+ 2013/2014+ 2015/2012<3
NT
1
NN
Nguyễn Ngọc Anh Minh
CTVHS
VIP
20 tháng 6 2017
\(B=\frac{2013-1}{2013}+\frac{2014-1}{2014}+\frac{2012+3}{2012}\)
\(B=1-\frac{1}{2013}+1-\frac{1}{2014}+1+\frac{3}{2012}=3+\frac{3}{2012}-\left(\frac{1}{2013}+\frac{1}{2014}\right)\)
Ta có
\(\frac{1}{2013}< \frac{1}{2012};\frac{1}{2014}< \frac{1}{2012}\Rightarrow\frac{1}{2013}+\frac{1}{2014}< \frac{2}{2012}\)
Mà \(\frac{3}{2012}-\frac{2}{2012}=\frac{1}{2012}>0\Rightarrow\frac{3}{2012}-\left(\frac{1}{2013}+\frac{1}{2014}\right)>0\)
=> B>3
NT
1
20 tháng 6 2017
\(B=\frac{2012}{2013}+\frac{2013}{2014}+\frac{2015}{2012}\)
\(B=\frac{2012}{2013}+\frac{2013}{2014}+\left(\frac{1}{2012}+\frac{1}{2012}+\frac{2013}{2012}\right)\)
\(B=\left(\frac{2012}{2013}+\frac{1}{2012}\right)+\left(\frac{2013}{2014}+\frac{1}{2012}\right)+\frac{2013}{2012}\)
\(3=1+1+1\)
\(\frac{2012}{2013}+\frac{1}{2012}>1\)
\(\frac{2013}{2014}+\frac{1}{2012}>1\)
\(\frac{2013}{2012}>1\)
vậy B > 3
MN
27 tháng 1 2016
\(N=\frac{2012+2013+2014}{2013+2014+2015}=\frac{2012}{2013+2014+2015}+\frac{2013}{2013+2014+2015}+\frac{2014}{2013+2014+2015}\)
Ta thấy: \(\frac{2012}{2013}>\frac{2012}{2013+2014+2015}\)
\(\frac{2013}{2014}>\frac{2013}{2013+2014+2015}\)
\(\frac{2014}{2015}>\frac{2014}{2013+2014+2015}\)
\(\Rightarrow M=\frac{2012}{2013}+\frac{2013}{2014}+\frac{2014}{2015}>N=\frac{2012}{2013+2014+2015}+\frac{2013}{2013+2014+2015}+\frac{2014}{2013+2014+2015}\)
Vậy M>N
C
0
NH
2
15 tháng 5 2016
Ta thấy B=2012+2013/2013+2014<1(vì 2012+2013<2013+2014)
Ta có A=2012/2013+2013/2014
A=1-1/2013+1-1/2014
A=(1+1)-(1/2013+1/2014)
A=2-(1/2013+1/2014)
Mà 1/2013<1/2;1/2014<1/2
=>1/2013+1/2014<1/2+1/2=1
=>2-(1/2013+1/2014)>1
=>A>1
Mà B<1
=>A>B
15 tháng 5 2016
\(B=\frac{2012+2013}{2013+2014}=\frac{2012}{2013+2014}+\frac{2013}{2013+2014}< \frac{2012}{2013}+\frac{2013}{2014}=A\)
Vậy B<A
12 tháng 3 2019
\(\frac{\frac{1}{2012}+\frac{1}{2013}-\frac{1}{2014}}{\frac{5}{2012}+\frac{5}{2013}-\frac{5}{2014}}-\frac{\frac{2}{2013}+\frac{2}{2014}-\frac{2}{2015}}{\frac{3}{2013}+\frac{3}{2014}-\frac{3}{2015}}\)
=\(\frac{\frac{1}{2012}+\frac{1}{2013}-\frac{1}{2014}}{5\left(\frac{1}{2012}+\frac{1}{2013}-\frac{1}{2014}\right)}-\frac{2\left(\frac{1}{2013}+\frac{1}{2014}-\frac{1}{2015}\right)}{3\left(\frac{1}{2013}+\frac{1}{2014}-\frac{1}{2015}\right)}=\frac{1}{5}-\frac{2}{3}=\frac{3}{15}-\frac{10}{15}=-\frac{7}{15}\)
LL
0
1/ Ta có : \(\frac{212121}{353535}=\frac{3.7.10101}{5.7.10101}=\frac{3}{5}=\frac{42}{70}\)
\(\frac{131313}{141414}=\frac{13.10101}{14.10101}=\frac{13}{14}=\frac{65}{70}\)
Vì 42 < 65 => \(\frac{42}{70}<\frac{65}{70}\) => \(\frac{212121}{353535}<\frac{131313}{141414}\)