\(a.\) \(\frac{4}{15}.\frac{7}{9}+\frac{4}{15}.\frac{2}{9}\)

\(=\frac{4}{15}\left(\frac{7}{9}+\frac{2}{9}\right)\)

\(=\frac{4}{15}.\frac{9}{9}\)

\(=\frac{4}{15}.1\)

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

\(b.\) \(\frac{13}{19}.\frac{23}{11}-\frac{13}{19}.\frac{8}{11}-\frac{13}{19}.\frac{4}{11}\)

\(=\frac{13}{19}\left(\frac{23}{11}-\frac{8}{11}-\frac{4}{11}\right)\)

\(=\frac{13}{19}.\frac{11}{11}\)

\(=\frac{13}{19}.1\)

\(=\frac{13}{19}\)

a)4/15 x(7/9+2/9)=4/15x1=4/15

b)13/19x(23/11-8/11-4/11)13/19x1=13/19

A) \(\frac{4}{15}x\frac{7}{9}+\frac{4}{15}x\frac{2}{9}\)

\(=\frac{28}{135}+\frac{8}{135}\)

\(=\frac{36}{135}=\frac{4}{15}\)

B) \(\frac{13}{19}x\frac{23}{11}-\frac{13}{19}x\frac{8}{11}-\frac{13}{19}x\frac{4}{11}\)

\(=\frac{299}{209}-\frac{104}{209}-\frac{52}{209}\)

\(=\frac{143}{209}\)

\(\frac{-11}{23}\cdot\frac{6}{7}+\frac{8}{7}\cdot\frac{-11}{23}-\frac{1}{23}\)

\(=\frac{-11}{23}\cdot\left(\frac{6}{7}+\frac{8}{7}\right)-\frac{1}{23}\)

\(=\frac{-11}{23}\cdot\frac{14}{7}-\frac{1}{23}\)

\(=\frac{-11}{23}\cdot2-\frac{1}{23}\)

\(=\frac{-22}{23}-\frac{1}{23}\)

\(=\frac{-22-1}{23}\)

\(=\frac{-23}{23}=-1\)

đáp án =(-1)

a: \(=\dfrac{17}{7}+\dfrac{2}{9}-\dfrac{10}{7}-\dfrac{5}{3}\cdot9=1+\dfrac{2}{9}-15=-14+\dfrac{2}{9}=-\dfrac{126}{9}+\dfrac{2}{9}=-\dfrac{124}{9}\)

b: \(=\dfrac{-11}{23}\left(\dfrac{6}{7}+\dfrac{8}{7}\right)-\dfrac{1}{23}=\dfrac{-22}{23}-\dfrac{1}{23}=-1\)

c: \(=\left(\dfrac{377}{-231}-\dfrac{123}{89}+\dfrac{34}{791}\right)\cdot\dfrac{4-3-1}{24}=0\)

d: \(=\dfrac{12}{7}\left(19+\dfrac{5}{8}-15-\dfrac{1}{4}\right)=\dfrac{12}{7}\cdot\dfrac{35}{8}=\dfrac{15}{2}\)

a,\(\frac{21}{25}.\frac{11}{9}.\frac{5}{7}=\frac{21.11.5}{25.9.7}=\frac{3.7.11.5}{5^2.3^2.7}=\frac{11}{5.3}=\frac{11}{15}\)

b,\(\frac{5}{23}.\frac{17}{26}+\frac{5}{23}.\frac{9}{26}=\frac{5}{23}.\left(\frac{17}{26}+\frac{9}{26}\right)=\frac{5}{23}.1=\frac{5}{23}\)

c, \(\left(\frac{3}{29}-\frac{1}{5}\right).\frac{29}{3}=\frac{3}{29}.\frac{29}{3}-\frac{1}{5}.\frac{29}{3}=1-\frac{29}{15}=-\frac{14}{15}\)

a , \(\frac{21}{25}\times\frac{11}{9}\times\frac{5}{7}\) 

\(=\frac{21\times11\times5}{25\times9\times7}\)

\(=\frac{3\times7\times11\times5}{5\times5\times3\times3\times7}\) 

\(=\frac{11}{5\times3}\) 

\(=\frac{11}{15}\) 

b ,   \(\frac{5}{23}\times\frac{17}{26}+\frac{5}{23}\times\frac{9}{26}\) 

\(=\frac{5}{23}\times\left(\frac{17}{26}+\frac{9}{26}\right)\)

\(=\frac{5}{23}\times\frac{26}{26}\) 

\(=\frac{5}{23}\times1\) 

\(=\frac{5}{23}\) 

c , \(\left(\frac{3}{29}-\frac{1}{5}\right)\times\frac{29}{3}\) 

\(=\frac{3}{29}\times\frac{29}{3}-\frac{1}{5}\times\frac{29}{3}\) 

\(=1-\frac{29}{15}\) 

\(A=\frac{17}{23}\cdot\frac{8}{16}\cdot\frac{23}{17}\cdot\left(-80\right)\cdot\frac{3}{4}\)\(=\frac{17\cdot4\cdot2\cdot23\cdot16\cdot\left(-5\right)\cdot3}{23\cdot16\cdot17\cdot4}\)

=> \(A=\frac{2\cdot\left(-5\right)\cdot3}{1}=-30\)

\(B=\left(\frac{13}{23}+\frac{1313}{2323}-\frac{131313}{232323}\right)\left(\frac{1}{3}+\frac{1}{4}-\frac{7}{12}\right)\)

=> \(B=\left(\frac{13}{23}+\frac{1313}{2323}-\frac{131313}{232323}\right)\left(\frac{7}{12}-\frac{7}{12}\right)\)

=> \(B=\left(\frac{13}{23}+\frac{1313}{2323}-\frac{131313}{232323}\right)\cdot0=0\)

a)\(A=\frac{17}{23}.\frac{8}{16}.\frac{23}{17}.\left(-80\right).\frac{3}{4}\)

    \(A=\left(\frac{17}{23}.\frac{23}{17}\right).\left(\frac{8}{16}.\frac{3}{4}\right).\left(-80\right)\)

     \(A=\frac{3}{8}.\left(-80\right)\)

     \(A=-30\)

b)\(C=\left(\frac{13}{23}+\frac{1313}{2323}-\frac{131313}{232323}\right).\left(\frac{1}{3}+\frac{1}{4}-\frac{7}{12}\right)\)

   \(C=\left(\frac{13}{23}+\frac{1313}{2323}-\frac{131313}{232323}\right).0\)

   \(C=0\)

a) \(\frac{-3}{7}+\frac{15}{26}-\left(\frac{2}{13}-\frac{3}{7}\right)=\frac{-3}{7}+\frac{15}{26}-\frac{2}{13}+\frac{3}{7}=\left(\frac{-3}{7}+\frac{3}{7}\right)+\left(\frac{15}{26}-\frac{2}{13}\right)\)

\(=\frac{15-4}{26}=\frac{11}{26}\)

c) \(\frac{-11}{23}.\frac{6}{7}+\frac{8}{7}.\frac{-11}{23}-\frac{1}{23}=\frac{-11}{23}.\left(\frac{6}{7}+\frac{8}{7}\right)-\frac{1}{23}\)

\(=\frac{-11}{23}.2-\frac{1}{23}=\frac{-22-1}{23}=\frac{-23}{23}=-1\)

d) Đặt \(\frac{377}{-231}-\frac{123}{89}+\frac{34}{791}=A\)

Ta có: \(A.\left(\frac{1}{6}-\frac{1}{8}-\frac{1}{24}\right)=A.\left(\frac{4-3-1}{24}\right)=A.0=0\)

1)

\(2.\frac{3}{7}+\left(\frac{2}{9}-1\frac{3}{7}\right)-\frac{5}{3}:\frac{1}{9}\)

\(=\frac{6}{7}+\frac{2}{9}-\frac{10}{7}-\frac{5}{3}.9\)

\(=\left(\frac{6}{7}-\frac{10}{7}\right)+\frac{2}{9}-15\)

\(=\frac{-4}{7}+\frac{2}{9}-\frac{15}{1}\)

\(=\frac{-36}{63}+\frac{14}{63}-\frac{945}{63}\)

\(=\frac{-967}{63}\)

2)

\(-\frac{11}{23}.\frac{6}{7}+\frac{8}{7}.\frac{-11}{23}-\frac{1}{23}\)

\(=\frac{-11}{23}\left(\frac{6}{7}+\frac{8}{7}\right)-\frac{1}{23}\)

\(=\frac{-11}{23}.2-\frac{1}{23}\)

\(=\frac{-22}{23}-\frac{1}{23}\)

\(=\frac{-23}{23}\)

\(=-1\)

3)

\(\left(\frac{377}{-231}-\frac{123}{89}+\frac{34}{791}\right).\left(\frac{1}{6}-\frac{1}{8}-\frac{1}{24}\right)\)

\(=\left(\frac{377}{-231}-\frac{123}{89}+\frac{34}{791}\right).\left(\frac{4}{24}-\frac{3}{24}-\frac{1}{24}\right)\)

\(=\left(\frac{377}{-231}-\frac{123}{89}+\frac{34}{791}\right).\frac{0}{24}\)

\(=\left(\frac{377}{-231}-\frac{123}{89}+\frac{34}{791}\right).0\)

\(=0\)