\(a,\dfrac{53}{57}=\dfrac{53.10}{57.10}=\dfrac{530}{570}=1-\dfrac{40}{570}\\ \dfrac{531}{571}=1-\dfrac{40}{571}\\ Vì:\dfrac{40}{570}>\dfrac{40}{571}\Rightarrow1-\dfrac{40}{570}< 1-\dfrac{40}{571}\\ \Leftrightarrow\dfrac{53}{57}< \dfrac{531}{571}\)

\(b,\dfrac{25}{26}=\dfrac{25.1010}{26.1010}=\dfrac{25250}{26260}=1-\dfrac{1010}{26260}\\ \dfrac{25251}{26261}=1-\dfrac{1010}{26261}\\ Vì:\dfrac{1010}{26260}>\dfrac{1010}{26261}\Rightarrow1-\dfrac{1010}{26260}< \dfrac{1010}{26261}\\ \Leftrightarrow\dfrac{25}{26}< \dfrac{25251}{26261}\)

a) 

a = 53. 571 = 53. (531 + 40) = 53. 531 + 53. 40 = 53. 531 + 53. (10.4)

= 53. 531 + (53. 10). 4 = 53. 531 + 530. 4

b = 57. 531 = (53 + 4). 531 = 531. (53 + 4) = 531. 53 + 531. 4 

Vì 530 < 531 nên 530. 4 < 531. 4 do đó 53. 531 + 530. 4 < 531. 53 + 531. 4 hay a < b.

Vậy a < b.

b)

a = 25. 26 261 = 25. (26 260 + 1) = 25. 26 260 + 25. 1 = 25. (10. 2 626) + 25

= (25. 10). 2 626 + 25 

= 25. 10. (26. 101) + 25 = 10. 25. 26. 101 + 25;

b = 26. 25 251 = 26. (25 250 + 1) = 26. 25 250 + 26. 1 = 26. (10. 2 525) + 26

= 26. 10. 2 525 + 26 = 26. 10. 25. 101 + 26 = 10. 25. 26. 101 + 26;

Vì 25 < 26 nên 10. 25. 26. 101 + 25 < 10. 25. 26. 101 + 26 hay a < b.

Vậy a < b.

sorry chỉ làm đuoc 25/26 bé hon 25251/26261 

85 / 84 lớn hơn 23/53

85/84 lớn hơn 35/36

a)<

b)>

c)>

d)<

Ta có : \(\frac{2003.2004-1}{2003.2004}=\frac{2003.2004}{2003.2004}-\frac{1}{2003.2004}=1-\frac{1}{2003.2004}\)

            \(\frac{2004.2005-1}{2004.2005}=\frac{2004.2005}{2004.2005}-\frac{1}{2004.2005}=1-\frac{1}{2004.2005}\)

Vì \(\frac{1}{2003.2004}>\frac{1}{2004.2005}\)

Nên : \(\frac{2003.2004-1}{2003.2004}< \frac{2004.2005-1}{2004.2005}\)

câu 2003.2004 lớn hơn 2004.2005