\(\dfrac{\dfrac{1}{6}-\dfrac{1}{39}+\dfrac{1}{51}}{\dfrac{1}{8}-\dfrac{1}{52}+\dfrac{1}{68}}\)

\(\dfrac{11}{\dfrac{78}{\dfrac{11}{104}+\dfrac{1}{68}}}+\dfrac{1}{51}\)

\(\dfrac{71}{\dfrac{442}{\dfrac{213}{1768}}}\)\(\Rightarrow\dfrac{4}{3}\)

= \(\dfrac{4}{3}\)

Bài 1:

\(\dfrac{-13}{38}\) và \(\dfrac{29}{-88}\) 

\(\dfrac{-13}{38}=\dfrac{-13.29}{38.29}=\dfrac{-377}{1102}\) 

\(\dfrac{29}{-88}=\dfrac{-29}{88}=\dfrac{-29.13}{88.13}=\dfrac{-377}{1144}\) 

Vì \(\dfrac{-377}{1102}< \dfrac{-377}{1144}\) nên \(\dfrac{-13}{38}< \dfrac{29}{-88}\) 

\(\dfrac{-18}{31}\) và \(\dfrac{-1818}{3131}\) 

\(\dfrac{-18}{31}\) 

\(\dfrac{-1818}{3131}=\dfrac{-1818:101}{3131:101}=\dfrac{-18}{31}\) 

Vì \(\dfrac{-18}{31}=\dfrac{-18}{31}\) nên \(\dfrac{-18}{31}=\dfrac{-1818}{3131}\)

Bài 2:

a) \(\dfrac{-1}{39}+\dfrac{-1}{52}=\dfrac{-4}{156}+\dfrac{-3}{156}=\dfrac{-4+-3}{156}=\dfrac{-7}{156}\) 

b) \(\dfrac{-6}{9}+\dfrac{-12}{16}=\dfrac{-2}{3}+\dfrac{-3}{4}=\dfrac{-8}{12}+\dfrac{-9}{12}=\dfrac{-17}{12}\)

\(\dfrac{-1}{39}+\dfrac{-1}{52}=-\dfrac{7}{156}\)

\(\dfrac{-1}{39}+\dfrac{-1}{52}=\dfrac{-52}{2028}+\dfrac{-39}{2028}=\dfrac{\left(-52\right)+\left(-39\right)}{2028}=\dfrac{-91}{2028}=\dfrac{-7}{156}\)

Chúc bạn học tốt!

\(\dfrac{-1}{39}+\dfrac{-1}{52}=\dfrac{-52}{2028}+\dfrac{-39}{2028}=\dfrac{\left(-52\right)+\left(-39\right)}{2028}=\dfrac{-91}{2028}=\dfrac{-7}{156}\)

\(\dfrac{-1}{39}+\dfrac{-1}{52}=\dfrac{-52}{2028}+\dfrac{-39}{2028}=\dfrac{\left(-52+-39\right)}{2028}=\dfrac{-91}{2028}=\dfrac{-7}{156}\)

Chúc bạn học tốt!

a: \(A=\left[6\cdot\dfrac{1}{27}+3\cdot\dfrac{1}{3}+1\right]:\dfrac{-4}{3}\)

\(=\left(\dfrac{2}{9}+2\right)\cdot\dfrac{-3}{4}\)

\(=\dfrac{20}{9}\cdot\dfrac{-3}{4}=\dfrac{-60}{36}=\dfrac{-5}{3}\)

b: \(B=\dfrac{\dfrac{1}{3}\left(\dfrac{1}{13}-\dfrac{1}{2}-\dfrac{1}{17}\right)}{-\dfrac{1}{4}\left(\dfrac{1}{13}-\dfrac{1}{2}-\dfrac{1}{17}\right)}:\dfrac{11}{6}\)

\(=\dfrac{-1}{3}:\dfrac{1}{4}\cdot\dfrac{6}{11}=\dfrac{-4}{3}\cdot\dfrac{6}{11}=\dfrac{-24}{33}=\dfrac{-8}{11}\)

1

a. B

b. C

c. D

a) \(\dfrac{-1}{39}+\dfrac{-1}{52}=\dfrac{-4}{156}+\dfrac{-3}{156}=\dfrac{-7}{156}\)

b) \(\dfrac{-6}{9}+\dfrac{-12}{16}=\dfrac{-2}{3}+\dfrac{-3}{4}=\dfrac{-8}{12}+\dfrac{-9}{12}=\dfrac{-17}{12}\)

c) \(\dfrac{-2}{5}-\dfrac{-3}{11}=\dfrac{-22}{55}-\dfrac{-15}{55}=\dfrac{-7}{55}\)

d) \(\dfrac{-34}{37}.\dfrac{74}{-85}=\dfrac{4}{5}\)

e) \(\dfrac{-5}{9}:\dfrac{-7}{18}=\dfrac{-5}{9}.\dfrac{18}{-7}=\dfrac{10}{7}\)

Ta có: \(\dfrac{-1}{3}\cdot\dfrac{141}{17}-\dfrac{39}{3}\cdot\dfrac{-1}{17}\)

\(=\dfrac{-1}{3}\cdot\dfrac{141}{17}-\dfrac{-1}{3}\cdot\dfrac{39}{17}\)

\(=\dfrac{-1}{3}\cdot\left(\dfrac{141}{17}-\dfrac{39}{17}\right)\)

\(=\dfrac{-1}{3}\cdot6=-2\)