Co cau khac ko de lan thit nguoi rat ngon 🤔

Soa ko ai tra loi cau hoi nay vay 

a) \(\dfrac{2}{5}+\dfrac{11}{15}=\dfrac{6}{15}+\dfrac{11}{15}=\dfrac{17}{15}\)

b) \(\dfrac{7}{8}-\dfrac{7}{9}=\dfrac{63}{72}-\dfrac{56}{72}=\dfrac{7}{72}\)

c) \(\dfrac{11}{13}\cdot\dfrac{26}{31}=\dfrac{26}{13}\cdot\dfrac{11}{31}=\dfrac{22}{31}\)

d) \(\dfrac{1}{2}:\dfrac{1}{3}\cdot\dfrac{2}{5}=\dfrac{1}{2}\cdot3\cdot\dfrac{2}{5}=\dfrac{3}{5}\)

a ) 2/5 + 11/15 = 6/15 + 11/ 15 = 17/15.

b ) 7/8 -7/9 = 63/72 -56/72 = 7/72.

c ) 11/13 x 26/31 = 22/31

d ) 1/2 : 1/3 x 2/5= 1/2 x 3/1 x 2/5 = 3/5

đúng thì tick mình nhé!!! cảm ơn bạn

a) \(\dfrac{{ - 1}}{{13}} + \dfrac{9}{{13}}\)

\( = \dfrac{{ - 1 + 9}}{{13}} = \dfrac{8}{{13}}\)

b) \(\dfrac{{ - 3}}{8} + \dfrac{5}{{12}}\)

\(\begin{array}{l} = \dfrac{{ - 3.3}}{{8.3}} + \dfrac{{5.2}}{{12.2}}\\ = \dfrac{{ - 9}}{{24}} + \dfrac{{10}}{{24}} = \dfrac{1}{{24}}\end{array}\

a) \(\dfrac{-1}{13}+\dfrac{9}{13}=\dfrac{\left(-1\right)+9}{13}=\dfrac{8}{13}\)

b) \(\dfrac{-3}{8}+\dfrac{5}{12}=\dfrac{-9}{24}+\dfrac{10}{24}=\dfrac{\left(-9\right)+10}{24}=\dfrac{1}{24}\)

a) Ta có: \(\dfrac{-5}{7}\left(\dfrac{14}{5}-\dfrac{7}{10}\right):\left|-\dfrac{2}{3}\right|-\dfrac{3}{4}\left(\dfrac{8}{9}+\dfrac{16}{3}\right)+\dfrac{10}{3}\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\)

\(=\dfrac{-5}{7}\cdot\dfrac{3}{2}\cdot\dfrac{21}{10}-\dfrac{3}{4}\cdot\dfrac{56}{3}+\dfrac{10}{3}\cdot\dfrac{8}{15}\)

\(=\dfrac{-9}{4}-14+\dfrac{16}{9}\)

\(=\dfrac{-1621}{126}\)

b) Ta có: \(\dfrac{17}{-26}\cdot\left(\dfrac{1}{6}-\dfrac{5}{3}\right):\dfrac{17}{13}-\dfrac{20}{3}\left(\dfrac{2}{5}-\dfrac{1}{4}\right)+\dfrac{2}{3}\left(\dfrac{6}{5}-\dfrac{9}{2}\right)\)

\(=\dfrac{-17}{26}\cdot\dfrac{13}{17}\cdot\dfrac{-3}{2}-\dfrac{20}{3}\cdot\dfrac{3}{20}+\dfrac{2}{3}\cdot\dfrac{-33}{10}\)

\(=\dfrac{3}{4}-1-\dfrac{11}{5}\)

\(=-\dfrac{49}{20}\)

a: =27/45-20/45=7/45

b: \(=\dfrac{3}{5}+\dfrac{30}{40}=\dfrac{3}{5}+\dfrac{3}{4}=\dfrac{12}{20}+\dfrac{15}{20}=\dfrac{27}{20}\)

c: \(=\dfrac{8}{13}\left(\dfrac{7}{2}-\dfrac{5}{2}+1\right)=\dfrac{8}{13}\cdot2=\dfrac{16}{13}\)

d: \(=\dfrac{9}{23}\left(\dfrac{5}{17}-\dfrac{22}{17}\right)+11+\dfrac{9}{23}=11\)

a) \(\dfrac{3}{5}+\dfrac{-4}{9}=\dfrac{27}{45}+\dfrac{-20}{45}=\dfrac{7}{45}\)

b) \(\dfrac{3}{5}+\dfrac{2}{5}.\dfrac{15}{8}=1.\dfrac{15}{8}=\dfrac{15}{8}\)

c) \(\dfrac{7}{2}.\dfrac{8}{13}+\dfrac{8}{13}.\dfrac{-5}{2}+\dfrac{8}{13}=\dfrac{8}{13}.\left(\dfrac{7}{2}+\dfrac{-5}{2}\right)=\dfrac{8}{13}.1=\dfrac{8}{13}\)

d) \(\dfrac{-5}{17}.\dfrac{-9}{23}+\dfrac{9}{23}.\dfrac{-22}{17}+11\dfrac{9}{23}=\dfrac{9}{23}.\left(\dfrac{-5}{17}+\dfrac{-22}{17}\right)=\dfrac{-243}{391}\)