ko biết sao  tôi ấn vô cập nhập thì nó lại hiện lên nhưng đăng lại thì nó ko có

\(1-x=\dfrac{49}{65}\cdot\dfrac{5}{7}\)

\(1-x=\dfrac{245}{455}\)

\(1-x=\dfrac{7}{13}\)

   \(-x=\dfrac{7}{13}-1\)

   \(-x=-\dfrac{6}{13}\)

      \(x=-\dfrac{6}{13}:\left(-1\right)\)

      \(x=\dfrac{6}{13}.\)

\(Vậy....\)

\(\dfrac{x}{17}=\dfrac{28}{9}\cdot\dfrac{-9}{17}\)

\(\dfrac{x}{17}=-\dfrac{28}{9}\cdot\dfrac{9}{17}\)

\(\dfrac{x}{17}=-\dfrac{28}{17}\)

   \(x=17\left(-\dfrac{28}{17}\right)\)

   \(x=-28\)

\(Vậy.....\)

\(=\left(64-32\right)^2=32^2=1024.\)

\(A=\dfrac{7}{12}+\dfrac{5}{12}:6-\dfrac{11}{36}\)\(=\left(\dfrac{7}{12}+\dfrac{5}{12}\right):6-\dfrac{11}{36}=1:6-\dfrac{11}{36}=\dfrac{1}{6}-\dfrac{11}{36}=-\dfrac{5}{36}.\)

\(B=\left(\dfrac{4}{5}+\dfrac{1}{2}\right):\left(\dfrac{3}{13}-\dfrac{8}{13}\right)=\dfrac{13}{10}:\left(-\dfrac{5}{13}\right)=-\dfrac{169}{50}.\)

\(C=\left(\dfrac{2}{3}-\dfrac{1}{4}+\dfrac{5}{11}\right):\left(\dfrac{5}{12}+1-\dfrac{7}{11}\right)\)\(=\dfrac{115}{132}:\dfrac{103}{132}=\dfrac{115}{103}.\)'

\(D=1\dfrac{3}{8}+\dfrac{1}{8}:\left(0,75-\dfrac{1}{2}\right)-25\%\cdot\dfrac{1}{2}\)

.......................

\(a.=\left(\dfrac{-3}{5}+\dfrac{-4}{5}+\dfrac{7}{5}\right)+\dfrac{7}{21}=\dfrac{7}{21}.\)

\(b.\dfrac{-3}{17}+\left(\dfrac{2}{3}+\dfrac{3}{17}\right)=\left(\dfrac{-3}{17}+\dfrac{3}{17}\right)+\dfrac{2}{3}=\dfrac{2}{3}.\)

\(c.=\left(\dfrac{-5}{21}+\dfrac{-16}{21}\right)+1=-1+1=0.\)

\(d.=\left(\dfrac{5}{7}+\dfrac{-12}{7}\right)+\left(\dfrac{9}{23}+\dfrac{14}{23}\right)=-1+1=0\)

\(e.=\left(\dfrac{3}{17}+\dfrac{14}{17}\right)+\left(\dfrac{-5}{13}+\dfrac{-8}{13}\right)+\left(\dfrac{-18}{35}+\dfrac{17}{-35}\right)\)

\(=1+\left(-1\right)+\left(-1\right)=-1.\)

\(f.=\dfrac{-1}{16}+\dfrac{-5}{16}+\dfrac{-10}{16}=-1.\)

\(g.=\left(\dfrac{-4}{11}\cdot\dfrac{11}{-4}\right)\cdot\dfrac{5}{15}=1\cdot\dfrac{5}{15}=\dfrac{1}{3}.\)

\(h.=\dfrac{7}{36}+\dfrac{8}{9}-\dfrac{2}{3}=\dfrac{7}{36}+\dfrac{32}{36}-\dfrac{24}{36}=\dfrac{15}{36}=\dfrac{5}{12}.\)

\(i.=\dfrac{4}{7}-\dfrac{5}{8}-\dfrac{3}{28}=\dfrac{32}{56}-\dfrac{35}{56}-\dfrac{6}{56}=-\dfrac{9}{56}.\)

\(l.=-\dfrac{6}{11}:\dfrac{12}{55}=-\dfrac{5}{2}.\)

\(-\dfrac{2}{3}-\dfrac{1}{3}\left(2x-5\right)=\dfrac{3}{2}\)

       \(-\dfrac{1}{3}\left(2x-5\right)=\dfrac{3}{2}+\dfrac{2}{3}\)

       \(-\dfrac{1}{3}\left(2x-5\right)=\dfrac{13}{6}\)

                \(2x-5=-\dfrac{13}{2}\)

                       \(2x=-\dfrac{13}{2}+5\)

                       \(2x=-\dfrac{3}{2}\)

                         \(x=-\dfrac{3}{2}:2\)

                         \(x=-\dfrac{3}{4}.\)

\(Vậy.....\)

\(a.257+149-57-49=257-57+149-49=200+100=300.\)

\(b.918-142-258=918-400=518.\)

\(c.26\cdot7-17\cdot9+13\cdot26-17\cdot11\)

\(=182-153+338-187=180.\)

\(d.1754:17-74:17+20:17\)

\(=\left(1754-74+20\right):17=1700:17=100.\)