a)\(\dfrac{5}{7}+\dfrac{4}{9}=\dfrac{45}{63}+\dfrac{28}{63}=\dfrac{73}{63}\) ; \(\dfrac{9}{11}+\dfrac{3}{8}=\dfrac{72}{88}+\dfrac{33}{88}=\dfrac{105}{88}\)

\(\dfrac{4}{5}-\dfrac{2}{3}=\dfrac{12}{15}-\dfrac{10}{15}=\dfrac{2}{15}\); \(\dfrac{16}{25}-\dfrac{2}{5}=\dfrac{16}{25}-\dfrac{10}{25}=\dfrac{6}{25}\)

b)\(5+\dfrac{3}{5}=\dfrac{25}{5}+\dfrac{3}{5}=\dfrac{28}{5};10-\dfrac{9}{16}=\dfrac{160}{16}-\dfrac{9}{16}=\dfrac{151}{16}\)

\(\dfrac{2}{3}-\left(\dfrac{1}{6}+\dfrac{1}{8}\right)=\dfrac{2}{3}-\left(\dfrac{8}{48}+\dfrac{6}{48}\right)=\dfrac{2}{3}-\dfrac{14}{48}=\dfrac{32}{48}-\dfrac{14}{48}=\dfrac{3}{8}\)

a,

\(=\frac{1+2+3+4+5+6+7+8+9}{10}=\frac{45}{10}=\frac{9}{2}\)

b,\(=9\times\left(\frac{26\times10101}{27\times10101}+\frac{8\times11111}{9\times11111}\right)=9\times\left(\frac{26}{27}+\frac{8}{9}\right)=9\times\frac{50}{27}=\frac{50}{3}\)

k cho mk nha!!!!!!!!!!!!!

Mk cần gấp các bạn ơi !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!?

Chịu

Thực hiện phép chịu...

\(\frac{1}{2}:\frac{3}{2}:\frac{5}{4}:\frac{6}{5}:\frac{7}{6}:\frac{8}{7}\)

\(=\frac{1}{2}\cdot\frac{2}{3}\cdot\frac{4}{5}\cdot\frac{5}{6}\cdot\frac{6}{7}\cdot\frac{7}{8}\)

\(=\frac{1\cdot\left(2\cdot5\cdot6\cdot7\right)}{8\cdot3\cdot\left(2\cdot5\cdot6\cdot7\right)}\)

\(=\frac{1}{24}\)

\(\frac{1}{2}\cdot\frac{2}{3}\cdot\frac{3}{4}\cdot\frac{4}{5}\cdot\frac{5}{6}\cdot\frac{6}{7}\cdot\frac{7}{8}\cdot\frac{8}{9}\cdot\frac{9}{10}\)

\(=\frac{1\cdot\left(2\cdot3\cdot4\cdot5\cdot6\cdot7\cdot8\cdot9\right)}{\left(2\cdot3\cdot4\cdot5\cdot6\cdot7\cdot8\cdot9\right)\cdot10}\)

\(=\frac{1}{10}\)

ps <\(\frac{1}{2}\) là:

\(\frac{1}{10}\frac{2}{10}\)

\(\frac{2}{5};\frac{9}{20};\frac{1}{10}\)là những phân số bé hơn \(\frac{1}{2}\)

Chúc bạn học giỏi nha!!!

K cho mik vs nhé

a Đ

b S

c S

d Đ

a ) S 

b ) Đ

c ) S

d ) Đ

k cho mk nhé 

\(\frac{4}{5}+\left(x:\frac{2}{3}-\frac{1}{2}\right)=\frac{9}{10}\)

\(x:\frac{2}{3}-\frac{1}{2}=\frac{9}{10}-\frac{4}{5}\)

\(x:\frac{2}{3}-\frac{1}{2}=\frac{1}{10}\)

\(x:\frac{2}{3}=\frac{1}{10}-\frac{1}{2}\)

\(x:\frac{2}{3}=\frac{-2}{5}\)

\(x=\frac{-2}{5}X\frac{2}{3}\)

\(x=\frac{-4}{15}\)

\(\frac{4}{5}+\left(x:\frac{2}{3}-\frac{1}{2}\right)=\frac{9}{10}\)

\(x:\frac{2}{3}-\frac{1}{2}=\frac{1}{10}\)

\(x:\frac{2}{3}=\frac{3}{5}\)

\(x=\frac{2}{5}\)

\(x+\frac{2}{3}=\frac{9}{11}\)

\(x=\frac{9}{11}-\frac{2}{3}\)

\(x=\frac{5}{33}\)

\(x-\frac{3}{10}=\frac{4}{15}\)

\(x=\frac{3}{10}-\frac{4}{15}\)

\(x=\frac{1}{10}\)

\(x\times\frac{1}{7}=\frac{5}{6}\)

\(x=\frac{5}{6}:\frac{1}{7}\)

\(x=\frac{35}{6}\)

\(x:\frac{3}{5}=\frac{1}{6}\)

\(x=\frac{3}{5}.\frac{1}{6}\)

\(x=\frac{1}{10}\)

+, \(x+\frac{2}{3}=\frac{9}{11}\)

\(x=\frac{9}{11}-\frac{2}{3}=\frac{5}{33}\)

+, \(x-\frac{3}{10}=\frac{4}{15}\)

\(x=\frac{4}{15}+\frac{3}{10}=\frac{17}{30}\)

+, \(x\cdot\frac{1}{7}=\frac{5}{6}\)

\(x=\frac{5}{6}:\frac{1}{7}=\frac{5}{6}.\frac{7}{1}=\frac{35}{6}\)

+,\(x:\frac{3}{5}=\frac{1}{6}\)

\(x=\frac{1}{6}\cdot\frac{3}{5}=\frac{3}{30}=\frac{1}{10}\)

Bài 5:

Bài giải

Bác An đã bán được số gạo là:

\(45\times\frac{2}{5}=18\left(kg\right)\)

Bác An còn lại số gạo là:

\(45-18=27\left(kg\right)\)

     Đ/S: 27 kg

Bài 1:

\(\frac{3}{4}-\frac{1}{6}=\frac{7}{12}\)

Bài 2:

\(\frac{9}{10}-x=\frac{1}{3}\)

\(x=\frac{9}{10}-\frac{1}{3}\)

\(x=\frac{17}{30}\)

Bài 3:

\(\frac{9}{8}-\frac{9}{14}=\frac{27}{56}\)

Bài 4:

\(\frac{4}{7}\times\frac{5}{3}=\frac{20}{21}\)

Bài 5:

Bài giải

Bác An đã bán được số gạo là: