12/25 < 25/49

13/15 > 133/155

a) Ta có \(\dfrac{23}{27}>\dfrac{23}{29};\dfrac{23}{29}>\dfrac{22}{29}\)

Vậy \(\dfrac{23}{27}>\dfrac{22}{29}\)

b) Ta có \(\dfrac{15}{25}=1-\dfrac{2}{5}\)

\(\dfrac{25}{49}=1-\dfrac{24}{49}\)

Vì \(\dfrac{2}{5}=\dfrac{24}{60}< \dfrac{24}{49}\)

Vậy \(\dfrac{15}{25}>\dfrac{25}{49}\)

23/27 lớn hơn 22/29

15/25 lớn hơn 25/49

câu 1 : quy đồng 2 ps ta đc : \(\frac{621}{756},\frac{672}{756}\) mà \(\frac{621}{756}

-25/20 < 20/25

15/21 > 21/49

-19/49 > -23/47

12/25>25/49

Ta có : 

\(\frac{12}{25}< \frac{12}{29}\)

             \(\frac{12}{29}< \frac{25}{29}\)

=> \(\frac{12}{25}< \frac{12}{29}< \frac{25}{29}\)

Vậy \(\frac{12}{25}< \frac{25}{29}\)

\(\frac{12}{25}< \frac{25}{49}\)

TA CÓ 12*2=24<25, 2582=50>49

=>12/25<25/49

Ta có:

\(\frac{12}{25}< \frac{12}{24}=\frac{1}{2}\Rightarrow\frac{12}{25}< \frac{1}{2}\left(1\right)\)

\(\frac{25}{49}>\frac{25}{50}=\frac{1}{2}\Rightarrow\frac{25}{49}>\frac{1}{2}\left(2\right)\)

Từ \(\left(1\right)\)và\(\left(2\right)\)\(\Rightarrow\)\(\frac{12}{25}< \frac{1}{2}< \frac{25}{49}\)\(\Rightarrow\frac{12}{25}< \frac{25}{49}\)

NHỚ TK MK NHA

\(\frac{12}{25}\)= 12: 25 0,48 

\(\frac{25}{49}\)= 0,510..........

=> 0,48 < 0,510 => \(\frac{12}{25}\)<    \(\frac{25}{49}\)

Ta có:

\(\frac{25}{12}>\frac{24}{12}=2\)

\(\frac{49}{25}< \frac{50}{25}=2\)

Vì  \(\frac{25}{12}>2>\frac{49}{25}\) nên  \(\frac{25}{12}>\frac{49}{25}\)

Chúc bạn học tốt!