a) Vì 4 < 5 nên \(\frac{3}{4}>\frac{3}{5}\)

b) Vì 4 < 5 nên \(\frac{4}{7}< \frac{5}{7}\)

c) Ta có :

\(\frac{2}{7}=\frac{2\times5}{7\times5}=\frac{10}{35}\)

\(\frac{4}{5}=\frac{4\times7}{5\times7}=\frac{28}{35}\)

Vì 10 < 28 nên \(\frac{10}{35}< \frac{28}{35}\)hay \(\frac{2}{7}< \frac{4}{5}\)

d) Ta có :

\(\frac{8}{9}=\frac{8\times10}{9\times10}=\frac{80}{90}\)

\(\frac{9}{10}=\frac{9\times9}{10\times9}=\frac{81}{90}\)

Vì 80 < 81 nên \(\frac{80}{90}< \frac{81}{90}\)hay \(\frac{8}{9}< \frac{9}{10}\)

e) Ta có :

\(\frac{10}{9}=\frac{10\times2}{9\times2}=\frac{20}{18}\)

Vì 19 < 20 nên \(\frac{19}{18}< \frac{20}{18}\)hay \(\frac{19}{18}< \frac{10}{9}\)

f) Ta có :

\(\frac{8}{3}=\frac{8\times4}{3\times4}=\frac{32}{12}\)

\(\frac{5}{6}=\frac{5\times2}{6\times2}=\frac{10}{12}\)

Vì 32 > 10 nên \(\frac{32}{12}>\frac{10}{12}\)hay \(\frac{8}{3}>\frac{5}{6}\)

bn nào dài được đầu tiên mà đúng mik sẽ k cho bn đó nhé

a; Cách một: 

     \(\dfrac{2}{9}\) = \(\dfrac{2\times2}{9\times2}\) = \(\dfrac{4}{18}\)  < \(\dfrac{4}{10}\) Vậy \(\dfrac{2}{9}\) < \(\dfrac{4}{10}\)

     \(\dfrac{4}{9}\) = \(\dfrac{4\times3}{9\times3}\) = \(\dfrac{12}{27}\); \(\dfrac{6}{10}\) = \(\dfrac{6\times2}{10\times2}\) = \(\dfrac{12}{20}\) 

 Vì \(\dfrac{12}{27}\) < \(\dfrac{12}{20}\) vậy \(\dfrac{4}{9}\) < \(\dfrac{12}{20}\)

     \(\dfrac{3}{8}\) = \(\dfrac{3\times4}{8\times4}\) = \(\dfrac{12}{24}\);   \(\dfrac{4}{7}\) = \(\dfrac{4\times3}{7\times3}\) = \(\dfrac{12}{21}\)

Vậy \(\dfrac{3}{8}\) < \(\dfrac{4}{7}\)

    \(\dfrac{5}{9}\) = \(\dfrac{5\times7}{9\times7}\) = \(\dfrac{35}{63}\); \(\dfrac{7}{10}\) = \(\dfrac{7\times5}{10\times5}\) = \(\dfrac{35}{50}\)

Vì \(\dfrac{35}{63}\) < \(\dfrac{35}{50}\) vậy \(\dfrac{5}{9}\) < \(\dfrac{7}{10}\)

     Cách hai:

a; \(\dfrac{2}{9}\) = \(\dfrac{2\times10}{9\times10}\) = \(\dfrac{20}{90}\); \(\dfrac{4}{10}\)  = \(\dfrac{4\times9}{10\times9}\) = \(\dfrac{36}{90}\) 

Vì \(\dfrac{20}{90}\) < \(\dfrac{36}{90}\) vậy \(\dfrac{2}{9}\) < \(\dfrac{4}{10}\)

b; \(\dfrac{4}{9}\) = \(\dfrac{4\times10}{9\times10}\) = \(\dfrac{40}{90}\); \(\dfrac{6}{10}\) = \(\dfrac{6\times9}{10\times9}\) = \(\dfrac{54}{90}\)

   Vì \(\dfrac{40}{90}\) < \(\dfrac{54}{90}\) vậy \(\dfrac{4}{9}\) < \(\dfrac{6}{10}\)

c; \(\dfrac{3}{8}\) = \(\dfrac{3\times7}{8\times7}\) = \(\dfrac{21}{56}\); \(\dfrac{4}{7}\) =  \(\dfrac{4\times8}{7\times8}\) = \(\dfrac{32}{56}\)

Vì \(\dfrac{21}{56}\) < \(\dfrac{32}{56}\) vậy \(\dfrac{3}{8}\) < \(\dfrac{4}{7}\)

d; \(\dfrac{5}{9}\) = \(\dfrac{5\times10}{9\times10}\) = \(\dfrac{50}{90}\); \(\dfrac{7}{10}\) = \(\dfrac{7\times9}{10\times9}\) = \(\dfrac{63}{90}\)

Vì \(\dfrac{50}{90}\) < \(\dfrac{63}{90}\) vậy \(\dfrac{5}{9}\) < \(\dfrac{7}{10}\) 

a; Cách một: 

     \(\dfrac{2}{9}\) = \(\dfrac{2\times2}{9\times2}\) = \(\dfrac{4}{18}\)  < \(\dfrac{4}{10}\) Vậy \(\dfrac{2}{9}\) < \(\dfrac{4}{10}\)

     \(\dfrac{4}{9}\) = \(\dfrac{4\times3}{9\times3}\) = \(\dfrac{12}{27}\); \(\dfrac{6}{10}\) = \(\dfrac{6\times2}{10\times2}\) = \(\dfrac{12}{20}\) 

 Vì \(\dfrac{12}{27}\) < \(\dfrac{12}{20}\) vậy \(\dfrac{4}{9}\) < \(\dfrac{12}{20}\)

     \(\dfrac{3}{8}\) = \(\dfrac{3\times4}{8\times4}\) = \(\dfrac{12}{24}\);   \(\dfrac{4}{7}\) = \(\dfrac{4\times3}{7\times3}\) = \(\dfrac{12}{21}\)

Vậy \(\dfrac{3}{8}\) < \(\dfrac{4}{7}\)

    \(\dfrac{5}{9}\) = \(\dfrac{5\times7}{9\times7}\) = \(\dfrac{35}{63}\); \(\dfrac{7}{10}\) = \(\dfrac{7\times5}{10\times5}\) = \(\dfrac{35}{50}\)

Vì \(\dfrac{35}{63}\) < \(\dfrac{35}{50}\) vậy \(\dfrac{5}{9}\) < \(\dfrac{7}{10}\)

       Cách hai:

a; \(\dfrac{2}{9}\) = \(\dfrac{2\times10}{9\times10}\) = \(\dfrac{20}{90}\); \(\dfrac{4}{10}\)  = \(\dfrac{4\times9}{10\times9}\) = \(\dfrac{36}{90}\) 

Vì \(\dfrac{20}{90}\) < \(\dfrac{36}{90}\) vậy \(\dfrac{2}{9}\) < \(\dfrac{4}{10}\)

b; \(\dfrac{4}{9}\) = \(\dfrac{4\times10}{9\times10}\) = \(\dfrac{40}{90}\); \(\dfrac{6}{10}\) = \(\dfrac{6\times9}{10\times9}\) = \(\dfrac{54}{90}\)

   Vì \(\dfrac{40}{90}\) < \(\dfrac{54}{90}\) vậy \(\dfrac{4}{9}\) < \(\dfrac{6}{10}\)

c; \(\dfrac{3}{8}\) = \(\dfrac{3\times7}{8\times7}\) = \(\dfrac{21}{56}\); \(\dfrac{4}{7}\) =  \(\dfrac{4\times8}{7\times8}\) = \(\dfrac{32}{56}\)

Vì \(\dfrac{21}{56}\) < \(\dfrac{32}{56}\) vậy \(\dfrac{3}{8}\) < \(\dfrac{4}{7}\)

d; \(\dfrac{5}{9}\) = \(\dfrac{5\times10}{9\times10}\) = \(\dfrac{50}{90}\); \(\dfrac{7}{10}\) = \(\dfrac{7\times9}{10\times9}\) = \(\dfrac{63}{90}\)

Vì \(\dfrac{50}{90}\) < \(\dfrac{63}{90}\) vậy \(\dfrac{5}{9}\) < \(\dfrac{7}{10}\) 

a) 1/2
b) 18/17; 17/16; 16/15; 15/14; 14/13; 13/12; 10/9
Nhớ k cho mk nha

a)1/2

b)Vì 18/17 <17/16 <16/15<15/14< 14/13< 13/12< 10/9

Nên, ta có: 

18/17; 17/16; 16/15; 15/14; 14/13; 13/12; 10/9.

\(a,=\frac{7-1}{1.3.7}+\frac{9-3}{3.7.9}+\frac{13-7}{7.9.13}+\frac{15-9}{9.13.15}\)\(+\frac{19-13}{13.15.19}\)

\(=\frac{1}{1.3}-\frac{1}{3.7}+\frac{1}{3.7}-\frac{1}{7.9}+\frac{1}{7.9}-\frac{1}{9.13}+\frac{1}{9.13}-\frac{1}{13.15}+\frac{1}{13.15}-\frac{1}{15.19}\)

\(=\frac{1}{1.3}-\frac{1}{15.19}=\frac{95}{285}-\frac{1}{285}=\frac{94}{285}\)

\(b,=\frac{1}{6}.\left(\frac{6}{1.3.7}+\frac{6}{3.7.9}+\frac{6}{7.9.13}+\frac{6}{9.13.15}+\frac{6}{13.15.19}\right)\)

làm giống như trên

\(c,=\frac{1}{8}.\left(\frac{1}{1.2.3}+\frac{1}{2.3.4}+\frac{1}{3.4.5}+...+\frac{1}{48.49.50}\right)\)

\(=\frac{1}{16}.\left(\frac{2}{1.2.3}+\frac{2}{2.3.4}+\frac{2}{3.4.5}+...+\frac{2}{48.49.50}\right)\)

\(=\frac{1}{16}.\left(\frac{3-1}{1.2.3}+\frac{4-2}{2.3.4}+\frac{5-3}{3.4.5}+...+\frac{50-48}{48.49.50}\right)\)

\(=\frac{1}{16}.\left(\frac{1}{1.2}-\frac{1}{2.3}+\frac{1}{2.3}-\frac{1}{3.4}+\frac{1}{3.4}-\frac{1}{4.5}+...+\frac{1}{48.49}-\frac{1}{49.50}\right)\)

\(=\frac{1}{16}.\left(\frac{1}{2}-\frac{1}{2450}\right)=\frac{1}{16}.\left(\frac{1225}{2450}-\frac{1}{2450}\right)=\frac{153}{4900}\)

\(d,=\frac{5}{7}.\left(\frac{7}{1.5.8}+\frac{7}{5.8.12}+\frac{7}{8.12.15}+...+\frac{7}{33.36.40}\right)\)

\(=\frac{5}{7}.\left(\frac{8-1}{1.5.8}+\frac{12-5}{5.8.12}+\frac{15-8}{8.12.15}+...+\frac{40-33}{33.36.40}\right)\)

\(=\frac{5}{7}.\left(\frac{1}{1.5}-\frac{1}{5.8}+\frac{1}{5.8}-\frac{1}{8.12}+\frac{1}{8.12}-\frac{1}{12.15}+...+\frac{1}{33.36}-\frac{1}{36.40}\right)\)

\(=\frac{5}{7}.\left(\frac{1}{5}-\frac{1}{1440}\right)=\frac{5}{7}.\left(\frac{288}{1440}-\frac{1}{1440}\right)=\frac{41}{288}\)

P/S: . là nhân nha

sxasxsxxsxsxssxsxsxsxsx232332321322

\(5\frac{1}{2}>5\frac{1}{4}\)

\(12\frac{7}{12}< 12\frac{5}{8}\)

\(6\frac{5}{7}< 12\frac{5}{8}\)

\(9\frac{6}{7}>8\frac{7}{8}\)

#Yuki

a)ta có : 2017/2018 = (2018 - 1) / 2018 = 2018/2018 - 1/2018 = 1 - 1/2018

Lại có : 9/10 = (10-1)/10 = 10/10-1/10 = 1-1/10

Vì 2018>10 => 1/2018 < 1/10

=> 1-1/2018 > 1-1/10

=> 2017/2018 > 9/10

Vậy 2017/2018 > 9/10

b) ta có : 8/5 = (5+3)/5 = 5/5 + 3/5 = 1 + 3/5

  lại có : 2017/2014 = (2014+3)/2014 = 2014/2014 + 3/2014 = 1 + 3/2014

vì 5<2014 => 3/5 > 3/2014 => 1+ 3/5 > 1+ 3/2014

=> 8/5 > 2017/2014

vậy...

đó .bạn dựa vào đó làm mấy câu sau nha.Chúc bạn học giỏi.nếu bạn cần thì mk sẽ giải hết.

Giải bài 2b hộ với

Cac ban hay giup minh tra loi cau nay nhe !

mẹ cha nhà nó tưởng trả lời được rồi chứ mần câu các bạn giup bạn giải bài này nha ọe