`-5/7 . 2/11 + (-5)/7 . 9/11 + 1 5/7`

`= -5/7 . (2/11 + 9/11) + 1 5/7`

`= -5/7 . 1 + 1 + 5/7`

`= -5/7 + 5/7 + 1`

`=1`.

\(=\dfrac{-5}{11}.\dfrac{2}{7}+\dfrac{-5}{11}.\dfrac{9}{7}+\dfrac{12}{7}\)

\(=-\dfrac{5}{11}\left(\dfrac{2}{7}+\dfrac{9}{7}\right)+\dfrac{12}{7}=-\dfrac{5}{11}.\dfrac{11}{7}+\dfrac{12}{7}\)

\(=\dfrac{-5}{7}+\dfrac{12}{7}=\dfrac{7}{7}=1\)

B=(\(\dfrac{1}{5}\)-\(\dfrac{1}{5}\))+(\(\dfrac{3}{7}\)-\(\dfrac{3}{7}\))+(\(\dfrac{5}{9}\)-\(\dfrac{5}{9}\))+(\(\dfrac{2}{11}\)-\(\dfrac{2}{11}\))+(\(\dfrac{7}{13}\)-\(\dfrac{7}{13}\))+\(\dfrac{9}{16}\)

B=\(\dfrac{9}{16}\)

\(\dfrac{-9}{16}\) chứ

a: =-1/3+1/3=0

b: \(=\dfrac{4}{11}\left(-\dfrac{2}{7}-\dfrac{4}{7}-\dfrac{1}{7}\right)=\dfrac{4}{11}\cdot\left(-1\right)=-\dfrac{4}{11}\)

c: \(=10+\dfrac{5}{9}-3-\dfrac{5}{7}-4-\dfrac{5}{9}=3-\dfrac{5}{7}=\dfrac{16}{7}\)

d: \(=\dfrac{1}{3}+\dfrac{7}{4}-\dfrac{7}{4}+\dfrac{4}{5}=\dfrac{1}{3}+\dfrac{4}{5}=\dfrac{5+12}{15}=\dfrac{17}{15}\)

a: =-1/3+1/3=0

b: 

c: 

d: 

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

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

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

a: =-5/7(2/11+9/11)+12/7

=12/7-5/7

=7/7=1

b: \(=\dfrac{-12}{56}+\dfrac{35}{56}-\dfrac{28}{56}=\dfrac{-5}{56}\)

c: \(=\dfrac{1}{4}-\dfrac{5}{13}+\dfrac{2}{11}-\dfrac{8}{13}+\dfrac{3}{4}\)

=1-1+2/11

=2/11

d: \(=\dfrac{21}{31}+\dfrac{-16}{7}+\dfrac{44}{53}+\dfrac{10}{31}+\dfrac{9}{53}\)

=1+1-16/7

=-2/7

e: \(=\dfrac{\dfrac{4}{36}-\dfrac{30}{36}-\dfrac{144}{36}}{\dfrac{21}{36}-\dfrac{1}{36}-\dfrac{360}{36}}=\dfrac{-160}{-340}=\dfrac{8}{17}\)

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

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

\(\dfrac{1}{3}-\dfrac{3}{5}+\dfrac{5}{7}-\dfrac{7}{9}+\dfrac{9}{11}-\dfrac{11}{13}+\dfrac{13}{15}+\dfrac{11}{13}-\dfrac{9}{11}+\dfrac{7}{9}-\dfrac{5}{7}+\dfrac{3}{5}-\dfrac{1}{3}\)
\(=\left(\dfrac{1}{3}-\dfrac{1}{3}\right)-\left(\dfrac{3}{5}-\dfrac{3}{5}\right)+\left(\dfrac{5}{7}-\dfrac{5}{7}\right)-\left(\dfrac{7}{9}-\dfrac{7}{9}\right)+\left(\dfrac{9}{11}-\dfrac{9}{11}\right)-\left(\dfrac{11}{13}-\dfrac{11}{13}\right)+\dfrac{13}{15}\)
\(=\dfrac{13}{15}\)

31​−53​+75​−97​+119​−1311​+1513​+1311​−119​+97​−75​+53​−31​
=(13−13)−(35−35)+(57−57)−(79−79)+(911−911)−(1113−1113)+1315=(31​−31​)−(53​−53​)+(75

\(A=\left(\dfrac{1}{3}+\dfrac{3}{5}+\dfrac{1}{15}\right)-\left(\dfrac{3}{4}+\dfrac{2}{9}+\dfrac{1}{36}\right)+\dfrac{1}{64}\)

\(=\dfrac{5+9+1}{15}-\dfrac{27+8+1}{36}+\dfrac{1}{64}\)

=1/64