a: \(\frac{-1}{9}\cdot\frac{-3}{5}+\frac{5}{-6}\cdot\frac{-3}{5}-\frac72\cdot\frac35\)

\(=\frac19\cdot\frac35+\frac56\cdot\frac35-\frac72\cdot\frac35\)

\(=\frac35\left(\frac19+\frac56-\frac72\right)\)

\(=\frac35\left(\frac{2}{18}+\frac{15}{18}-\frac{63}{18}\right)=\frac35\cdot\frac{-46}{18}=\frac35\cdot\frac{-23}{9}=\frac{-23}{3\cdot5}=-\frac{23}{15}\)

b: Sửa đề: \(-\frac37\cdot\frac{15}{13}-\frac37\cdot\frac{11}{13}-\frac37\)

\(=-\frac37\left(\frac{15}{13}+\frac{11}{13}\right)-\frac37\)

\(=-\frac37\cdot2-\frac37=-\frac37\cdot3=-\frac97\)

Bài 1:

+) \(\dfrac{7}{8}\times y=\dfrac{3}{2}+\dfrac{6}{4}=3\)

\(y=3:\dfrac{7}{8}=\dfrac{24}{7}\)

+) \(\dfrac{1}{y}\times\left(\dfrac{2}{5}+\dfrac{1}{5}\right)=\dfrac{10}{3}\)

\(\dfrac{1}{y}=\dfrac{10}{3}:\dfrac{3}{5}=\dfrac{50}{9}\)

\(y=\dfrac{9}{50}\)

Bài 2:

+) \(=\dfrac{2}{5}\times\left(\dfrac{4}{7}+\dfrac{3}{7}\right)\)

\(=\dfrac{2}{5}\times\dfrac{7}{7}=\dfrac{2}{5}\)

+) \(\dfrac{2}{9}:\dfrac{2}{3}:\dfrac{3}{9}\)

\(\dfrac{2}{9}\times\dfrac{3}{2}\times\dfrac{9}{3}=1\)

a: =4/5+1/5+2/3+1/3=1+1=2

b: =17/12+7/12+29/7-8/7=3+2=5

c: =3/5+2/5+16/7-1/7-1/7

=1+2=3

d: =2/5+3/5+2/3+1/3+7/4+1/4

=1+1+2

=4

thanks

5, \(\dfrac{1}{7}.\dfrac{2}{5}+\dfrac{1}{7}.\dfrac{1}{5}+\dfrac{1}{7}.\dfrac{4}{5}\)

= \(\dfrac{1}{7}.\left(\dfrac{2}{5}+\dfrac{1}{5}+\dfrac{4}{5}\right)\)

= \(\dfrac{1}{7}\).1

=\(\dfrac{1}{7}\)

5) \(\dfrac{1}{7}.\dfrac{2}{5}+\dfrac{1}{7}.\dfrac{1}{5}+\dfrac{1}{7}.\dfrac{4}{5}\) = \(\dfrac{1}{7}.\left(\dfrac{2}{5}+\dfrac{1}{5}+\dfrac{4}{5}\right)\)

= \(\dfrac{1}{7}.\dfrac{7}{5}=\dfrac{1}{5}\)

Bài làm :

\(=\left(\dfrac{2}{7}+\dfrac{5}{7}\right)+\left(\dfrac{3}{11}-\dfrac{6}{11}\right)+\dfrac{1}{4}=\dfrac{5}{4}-\dfrac{3}{11}=\dfrac{55}{44}-\dfrac{12}{44}=\dfrac{43}{44}\)

`2/7-(-3)/11+5/7-1/(-4)-6/11`

`=2/7+3/11+5/7+1/4-6/11`

`=(2/7+5/7)+(3/11-6/11)+1/4`

`=7/7-3/11+1/4`

`=1-3/11+1/4`

`=44/44-12/44+11/44`

`=43/44`

a: \(=\dfrac{-2}{12}-\dfrac{5}{12}+\dfrac{7}{12}=0\)

b: \(=\left(\dfrac{4}{45}-\dfrac{1}{45}+\dfrac{7}{45}+\dfrac{4}{45}-\dfrac{2}{45}-\dfrac{9}{45}\right)=\dfrac{3}{45}=\dfrac{1}{15}\)

Sửa đề : \(M=\left(\dfrac{\dfrac{2}{5}-\dfrac{2}{9}+\dfrac{2}{11}}{\dfrac{7}{5}-\dfrac{7}{9}+\dfrac{7}{11}}-\dfrac{\dfrac{1}{3}-\dfrac{1}{3}+\dfrac{1}{5}}{1\dfrac{1}{6}-\dfrac{7}{6}+\dfrac{7}{10}}\right):\dfrac{2021}{2022}\)

\(M=\left(\dfrac{\dfrac{2}{5}-\dfrac{2}{9}+\dfrac{2}{11}}{\dfrac{7}{5}-\dfrac{7}{9}+\dfrac{7}{11}}-\dfrac{\dfrac{1}{3}-\dfrac{1}{3}+\dfrac{1}{5}}{1\dfrac{1}{6}-\dfrac{7}{6}+\dfrac{7}{10}}\right):\dfrac{2021}{2022}\\ =\left(\dfrac{2\left(\dfrac{1}{5}-\dfrac{1}{9}+\dfrac{1}{11}\right)}{7\left(\dfrac{1}{5}-\dfrac{1}{9}+\dfrac{7}{11}\right)}-\dfrac{\dfrac{1}{3}-\dfrac{1}{3}+\dfrac{1}{5}}{\dfrac{7}{6}-\dfrac{7}{6}+\dfrac{7}{10}}\right):\dfrac{2021}{2022}\\ =\left(\dfrac{2}{7}-\dfrac{\dfrac{1}{3}-\dfrac{1}{3}+\dfrac{1}{5}}{\dfrac{7}{2}\left(\dfrac{1}{3}-\dfrac{1}{3}+\dfrac{1}{5}\right)}\right):\dfrac{2021}{2020}\\ =\left(\dfrac{2}{7}-\dfrac{2}{7}\right):\dfrac{2021}{2022}=0\)

cảm ơn bạn mk nhầm đề

e: \(\frac25\cdot\frac13-\frac{2}{15}:\frac15+\frac35\cdot\frac13\)

\(=\frac{2}{15}+\frac{3}{15}-\frac{2}{15}\cdot5\)

\(=\frac{5}{15}-\frac{10}{15}=-\frac{5}{15}=-\frac13\)

d: \(19\frac58:\frac{7}{12}-15\frac14:\frac{7}{12}\)

\(=\left(19+\frac58-15-\frac14\right):\frac{7}{12}\)

\(=\left(4+\frac58-\frac28\right):\frac{7}{12}=\left(4+\frac38\right)\cdot\frac{12}{7}=\frac{35}{8}\cdot\frac{12}{7}=5\cdot\frac32=\frac{15}{2}\)

a: \(2\frac37+\left(\frac29-1\frac37\right)-\frac53:\frac19\)
\(=2+\frac37+\frac29-1-\frac37-\frac53\cdot9\)

\(=1+\frac29-5\cdot3=1-15+\frac29=-14+\frac29=\frac{-126+2}{9}=-\frac{124}{9}\)