\(\frac{2012}{1999}=\frac{1999+13}{1999}=1+\frac{13}{1999}\)

\(\frac{1999}{1986}=\frac{1986+13}{1986}=1+\frac{13}{1986}\)

Có \(1999>1986\Leftrightarrow\frac{13}{1999}< \frac{13}{1986}\)

Suy ra \(\frac{2012}{1999}< \frac{1999}{1986}\).

A. 13/5 = 2 + 3/5   ;  15/7 = 2 + 1/7

    3/5 > 1/7 =>  13/5 > 15/7

B. 2012/1999 = 1 + 13/1999  ;  1999/1986 = 1 + 13/1986

13/1999 < 13/1986 => 2012/1999 < 1999/1986

C. 33/17 = 1 + 16/17

    37/18 = 2 + 1/18

=> 33/17 < 37/18 =>  17/33 > 18/37

D. 405/203 = 1 + 202/203

    203/101 = 2 + 1/101

=> 405/203 < 203/101 => 203/405 > 101/203

2001/1999=1/2/1999

2007/2005=1/2/2005

 ta so sanh mau so hai phan so

cung tu mau lon hon thi be hon

vay:2001/1999>2007/2005

Ta có:

\(\dfrac{1119}{1999}=1-\dfrac{880}{1999}\)

\(\dfrac{1999}{2000}=1-\dfrac{1}{2000}\) 

Mà: \(\dfrac{1}{2000}< \dfrac{880}{1999}\)

\(\Rightarrow1-\dfrac{880}{1999}< 1-\dfrac{1}{2000}\)

\(\Rightarrow\dfrac{1119}{1999}< \dfrac{1999}{2000}\)

hello

a) 12/17 và 7/15

=>180/255 và 119/225

=>12/17<7/15

b)1999/2001 và 12/11

a) 

\(1-\frac{1998}{1999}=\frac{1}{1999}\)

\(1-\frac{1999}{2000}=\frac{1}{2000}\)

Vì \(\frac{1}{1999}>\frac{1}{2000}\)nên \(\frac{1998}{1999}< \frac{1999}{2000}\)

b) Ta có :

\(\frac{1999}{2001}< 1\)

\(\frac{12}{11}>1\)

Nên \(\frac{1999}{2001}< \frac{12}{11}\)

c) 

\(1-\frac{13}{27}=\frac{14}{27}\)

\(1-\frac{27}{41}=\frac{14}{41}\)

Vì \(\frac{14}{27}>\frac{14}{41}\)nên \(\frac{13}{27}< \frac{27}{41}\)

d) 

Ta có phân số trung gian là \(\frac{23}{45}\).

Ta có : \(\frac{23}{47}< \frac{23}{45}\) ; \(\frac{24}{45}>\frac{23}{45}\)

Nên \(\frac{23}{47}< \frac{24}{45}\)

có ai trả lời mik ko 

ai trả lời được mik liền

Ta có : \(1=\frac{1998}{1999}+\frac{1}{1999}\)

         \(1=\frac{1}{2000}+\frac{1999}{2000}\)

Mà \(\frac{1}{2000}< \frac{1}{1999}\)

Nên \(\frac{1999}{2000}>\frac{1998}{1999}\)