A.4/25 < 25/4

B. 2/9 và  < 9/2

A.4/25 < 25/4

 B. 2/9  <9/2

`a)75<77`

`=>1/75>1/77`

`=>37/75>37/77>35/77`

`b)7779>7569`

`=>1/7779<1/7569`

`=>3734/7569>3734/7779>2099/7779`

\(\sqrt{Ai}giúpmkvớiak\)

A.4/3 > 95/96

B.25/68 > 20/99

C. 9/50 <11/42

> 

> 

 <

A.4/3 > 95/96

B.25/68 >20/99

C. 9/50  <11/42

Ta có:  \(\frac{123}{124}< 1\)

            \(\frac{20142014}{20132013}=\frac{2014}{2013}>1\)

Vậy  \(\frac{123}{124}< \frac{20142014}{20132013}\)

p/s: chúc bạn học tốt

Ta có: \(\frac{20142014}{20132013}=\frac{2014}{2013}\)

Lại có: \(\frac{123}{124}=\frac{124-1}{124}=1-\frac{1}{124}\Rightarrow\frac{123}{124}< 1\) (1)

\(\frac{2014}{2013}=\frac{2013+1}{2013}=1+\frac{1}{2013}\Rightarrow\frac{2014}{2013}>1\)(2)

Từ (1)(2) => \(\frac{123}{123}< \frac{2014}{2013}hay\frac{123}{124}< \frac{20142014}{20132013}\)

A = \(\dfrac{3^{123}+1}{3^{125}+1}\)  Vì 3¹²³ + 1 < 2¹²⁵ + 1 Nên A = \(\dfrac{3^{123}+1}{3^{125}+1}\)< \(\dfrac{3^{123}+1+2}{3^{125}+1+2}\)

A < \(\dfrac{3^{123}+3}{3^{125}+3}\) = \(\dfrac{3.\left(3^{122}+1\right)}{3.\left(3^{124}+1\right)}\) = \(\dfrac{3^{122}+1}{3^{124}+1}\) = B

Vậy A < B 

Ta có : \(\frac{124124}{125125}=\frac{124124:1001}{125125:1001}=\frac{124}{125}\)

\(\frac{123}{124}=1-\frac{1}{124}\); \(\frac{124}{125}=1-\frac{1}{125}\)

Vì 1/124 < 1/125 => 123/124 > 123/125 => 123/124 > 124124/125125

ta có: \(\frac{124124}{125125}=\frac{124}{125}\)

Lại có: \(1-\frac{123}{124}=\frac{1}{124};1-\frac{124}{125}=\frac{1}{125}\)

\(\Rightarrow\frac{1}{124}>\frac{1}{125}\Rightarrow1-\frac{123}{124}>1-\frac{124}{125}\)

\(\Rightarrow\frac{123}{124}< \frac{124}{125}\Rightarrow\frac{123}{124}< \frac{124124}{125125}\)

So sánh 2 phân số : 123 / 124 và 124124 / 125125

124124 / 125125 = 124 / 125

123 / 124 = 1 - 123 / 124 = 1/124

124 / 125 = 1 - 124 / 125 = 1/125 

Vì 1/ 124 > 1/125 => 123/124 > 124124/125125

Vậy 123/124 > 124124/125125