1/4 . -3/5 - 7/5 *1/4 +5/2 * 1/5

= -3/20- 7/20 + 10/20

= 0/20

chắc thế

\(M=\dfrac{1,6:\left(1\dfrac{3}{5}.1,25\right)}{0,64-\dfrac{1}{25}}+\dfrac{\left(1,08-\dfrac{2}{25}\right):\dfrac{4}{7}}{\left(5\dfrac{5}{9}-2\dfrac{1}{4}\right).2\dfrac{1}{4}}+0,6.0,5:\dfrac{2}{5}\)

\(M=\dfrac{1,6:\left(\dfrac{8}{5}.1,25\right)}{0,64-\dfrac{1}{25}}+\dfrac{\left(1,08-\dfrac{2}{25}\right):\dfrac{4}{7}}{\left(\dfrac{50}{9}-\dfrac{9}{4}\right).\dfrac{35}{17}}+0,6.0,5:\dfrac{2}{5}\)

\(M=\dfrac{1,6:2}{0,64-\dfrac{1}{25}}+\dfrac{1:\dfrac{4}{7}}{\dfrac{119}{36}.\dfrac{35}{17}}+0,6.0,5:\dfrac{2}{5}\)

\(M=\dfrac{0,8}{0,6}+\dfrac{1,75}{\dfrac{245}{36}}+0,6.0,5:\dfrac{2}{5}\)

\(M=\dfrac{4}{3}+\dfrac{9}{35}+0,6.0,5:\dfrac{2}{5}\)

\(M=\dfrac{167}{105}+0,6.0,5:\dfrac{2}{5}\)

\(M=\dfrac{167}{105}+\dfrac{3}{10}:\dfrac{2}{5}\)

\(M=\dfrac{167}{105}+\dfrac{3}{4}\)

\(M=\dfrac{983}{420}.\)

Câu 1 : 

\(\dfrac{-25}{37}\&\dfrac{-20}{31}\)

Ta thấy \(\dfrac{-25}{37}< \dfrac{-20}{37}\)

mà \(\dfrac{-20}{37}< \dfrac{-20}{31}\)

\(\Rightarrow\dfrac{-25}{37}< \dfrac{-20}{31}\)

Câu 2 :

\(\dfrac{2}{3}\&\dfrac{5}{7}\)

\(\dfrac{2}{3}:\dfrac{5}{7}=\dfrac{2}{3}.\dfrac{7}{5}=\dfrac{14}{15}< 1\)

Ta thấy \(\dfrac{8}{13}:\dfrac{5}{7}=\dfrac{8}{13}.\dfrac{7}{5}=\dfrac{56}{65}< 1\)

\(E=\dfrac{98:\left(\dfrac{4}{5}\cdot\dfrac{5}{4}\right)}{\dfrac{16}{25}-\dfrac{1}{25}}+\dfrac{\left(\dfrac{27}{25}-\dfrac{2}{25}\right)\cdot\dfrac{7}{4}}{\left(\dfrac{59}{9}-\dfrac{13}{4}\right)\cdot\dfrac{36}{17}}\\ E=\dfrac{98}{\dfrac{3}{5}}+\dfrac{\dfrac{7}{4}}{\dfrac{119}{36}\cdot\dfrac{36}{17}}\\ E=\dfrac{490}{3}+\dfrac{\dfrac{7}{4}}{7}=\dfrac{490}{3}+\dfrac{1}{4}=\dfrac{1963}{12}\)

3\(\dfrac{1}{7}\) : \(\left\{\left[2-1\dfrac{3}{5}:\left(\dfrac{4}{3}-1,6\right)\right]-25\%\right\}\)

= \(\dfrac{22}{7}\) : \(\left\{\left[\dfrac{10}{5}-\dfrac{8}{5}:\left(\dfrac{4}{3}-\dfrac{8}{5}\right)\right]-\dfrac{1}{4}\right\}\)

= \(\dfrac{22}{7}\) : \(\left\{\left[\dfrac{10}{5}-\dfrac{8}{5}:\left(\dfrac{20}{15}-\dfrac{24}{15}\right)\right]-\dfrac{1}{4}\right\}\)

= \(\dfrac{22}{7}\) : \(\left\{\left[\dfrac{10}{5}-\dfrac{8}{5}:\dfrac{-4}{15}\right]-\dfrac{1}{4}\right\}\)

= \(\dfrac{22}{7}\) : \(\left\{\left[\dfrac{10}{5}-\dfrac{8}{5}.\dfrac{-15}{4}\right]-\dfrac{1}{4}\right\}\)

= \(\dfrac{22}{7}\) : \(\left\{\left[\dfrac{10}{5}-\dfrac{-30}{5}\right]-\dfrac{1}{4}\right\}\)

= \(\dfrac{22}{7}\) : \(\left\{8-\dfrac{1}{4}\right\}\)

= \(\dfrac{22}{7}\) : \(\left\{\dfrac{32}{4}-\dfrac{1}{4}\right\}\)

= \(\dfrac{22}{7}\) : \(\dfrac{31}{4}\)

= \(\dfrac{22}{7}\) . \(\dfrac{4}{31}\)

= \(\dfrac{88}{217}\)

Chúc bạn Kfkfj có một mùa hè tuyệt vời và học thật tốt!

\(A=\dfrac{1,6:\left(1\dfrac{3}{5}.1,25\right)}{0,64-\dfrac{1}{25}}+\dfrac{\left(1,08-\dfrac{2}{25}\right):\dfrac{4}{7}}{5\dfrac{5}{9}-2\dfrac{1}{4}.2\dfrac{2}{17}}+0,6.0,5:\dfrac{2}{5}\)

\(A=\dfrac{\dfrac{8}{5}:\left(\dfrac{8}{5}.\dfrac{5}{4}\right)}{\dfrac{64}{100}-\dfrac{4}{100}}+\dfrac{\left(\dfrac{108}{100}-\dfrac{8}{100}\right):\dfrac{4}{7}}{\left(\dfrac{50}{9}-\dfrac{9}{4}\right).\dfrac{36}{17}}+\dfrac{3.1.5}{5.2.2}\)

\(A=\dfrac{\dfrac{4}{5}}{\dfrac{60}{100}}+\dfrac{1:\dfrac{4}{7}}{\left(\dfrac{200}{36}-\dfrac{81}{36}\right).\dfrac{36}{17}}+\dfrac{3}{4}\)

\(A=\dfrac{\dfrac{4}{5}}{\dfrac{3}{5}}+\dfrac{\dfrac{7}{4}}{\dfrac{119}{36}.\dfrac{36}{17}}+\dfrac{3}{4}\)

\(A=\dfrac{4}{3}+\dfrac{\dfrac{7}{4}}{7}+\dfrac{3}{4}\)

\(A=\dfrac{16}{12}+\dfrac{3}{12}+\dfrac{9}{12}\)

\(A=\dfrac{28}{12}\) \(=\dfrac{7}{3}\)

a: \(=\dfrac{-7}{8}\left(\dfrac{3}{5}+\dfrac{2}{5}\right)+3+\dfrac{7}{8}=\dfrac{-7}{8}+\dfrac{7}{8}+3=3\)

b: \(=-\dfrac{8}{5}:\dfrac{5}{3}=-\dfrac{24}{25}\)

c: \(=\dfrac{6}{7}+\dfrac{1}{8}-\dfrac{3}{4}=\dfrac{6}{7}+\dfrac{1}{8}-\dfrac{6}{8}=\dfrac{6}{7}-\dfrac{5}{8}=\dfrac{48}{56}-\dfrac{35}{56}=\dfrac{13}{56}\)

a) \(\dfrac{-3}{8}-\dfrac{1}{8}:x=-5\dfrac{1}{4}-2\dfrac{1}{4}\)

\(\dfrac{-3}{8}-\dfrac{1}{8}:x=\dfrac{-21}{4}-\dfrac{9}{4}\)

\(\dfrac{-3}{8}-\dfrac{1}{8}:x=\dfrac{-15}{2}\)

\(\dfrac{1}{8}:x=\dfrac{-3}{8}-\dfrac{-15}{2}\)

\(\dfrac{1}{8}:x=\dfrac{57}{8}\)

\(x=\dfrac{1}{8}:\dfrac{57}{8}\)

\(x=\dfrac{1}{57}\)

b) \(\left(1\dfrac{1}{3}-25\%-\dfrac{5}{12}\right)-2x=1,6:\dfrac{3}{5}\)

\(\left(1\dfrac{1}{3}-\dfrac{1}{4}-\dfrac{5}{12}\right)-2x=\dfrac{8}{5}:\dfrac{3}{5}\)

\(\left(\dfrac{4}{3}-\dfrac{1}{4}-\dfrac{5}{12}\right)-2x=\dfrac{8}{3}\)

\(\left(\dfrac{13}{12}-\dfrac{5}{12}\right)-2x=\dfrac{8}{3}\)

\(\dfrac{2}{3}-2x=\dfrac{8}{3}\)

\(2x=\dfrac{2}{3}-\dfrac{8}{3}\)

\(2x=-2\)

\(x=\left(-2\right):2\)

\(x=-1\)

\(B=\left(1,6\cdot0,4\right)^2-\dfrac{57}{4}+\dfrac{7}{5}-\dfrac{7}{4}=\dfrac{256}{625}-16+\dfrac{7}{5}=-\dfrac{8869}{625}\)