\(\dfrac{20}{41}+\dfrac{13}{21}+\dfrac{21}{41}+\dfrac{8}{21}\)

\(=\left(\dfrac{20}{41}+\dfrac{21}{41}\right)+\left(\dfrac{13}{21}+\dfrac{8}{21}\right)\)

\(=\dfrac{41}{41}+\dfrac{21}{21}\)

\(=\dfrac{1}{1}+\dfrac{1}{1}\)

\(=1+1\)

\(=2\)

=5

\(\dfrac{\dfrac{36}{41}:\dfrac{9}{41}}{\dfrac{14}{21}:\dfrac{7}{21}}\) \(\times\) \(\dfrac{2}{5}\)

= \(\dfrac{\dfrac{36}{41}\times\dfrac{41}{9}}{\dfrac{14}{21}\times\dfrac{21}{7}}\) \(\times\) \(\dfrac{2}{5}\)

= \(\dfrac{4}{2}\) \(\times\) \(\dfrac{2}{5}\)

= \(\dfrac{4}{5}\)

\(\dfrac{5}{13}+\left(-\dfrac{5}{7}\right)+\left(-\dfrac{20}{41}\right)+\dfrac{8}{13}+\left(-\dfrac{21}{41}\right)\)

\(=\dfrac{5}{13}-\dfrac{5}{7}-\dfrac{20}{41}+\dfrac{8}{13}-\dfrac{21}{41}\)

\(=\left(\dfrac{5}{13}+\dfrac{8}{13}\right)-\left(\dfrac{20}{41}+\dfrac{21}{41}\right)-\dfrac{5}{7}\)

\(=\dfrac{13}{13}-\dfrac{41}{41}-\dfrac{5}{7}\)

\(=1-1-\dfrac{5}{7}\)

\(=0+\dfrac{5}{7}\)

\(=\dfrac{5}{7}\)

\(\dfrac{5}{13}+\dfrac{-5}{7}+\dfrac{-20}{41}+\dfrac{8}{13}+\dfrac{-21}{41}\)

\(=\left(\dfrac{5}{13}+\dfrac{8}{13}\right)+\left(\dfrac{-20}{41}+\dfrac{-21}{41}\right)+\dfrac{-5}{7}\)

\(=1+\left(-1\right)+\dfrac{-5}{7}\)

\(=\dfrac{-5}{7}\)

\(#PaooNqoccc\)

-0.71428571428

Trả lời :

5/13 + - 5/7 + - 20/41 + 8/13 - 21/41 = -0.71428571428

~ Học tốt ~

\(\dfrac{5}{13}+\dfrac{-5}{17}+\dfrac{-20}{41}+\dfrac{8}{13}+\dfrac{-21}{41}\)

\(=\left(\dfrac{5}{13}+\dfrac{8}{13}\right)+\dfrac{-5}{17}+\left(\dfrac{-20}{41}-\dfrac{21}{41}\right)\)

\(=\dfrac{13}{13}+\dfrac{-5}{17}+\dfrac{-41}{41}\)

\(=1-\dfrac{5}{17}-1\)

\(=-\dfrac{5}{17}\)

= -103/273

= 0

= -5/7

5.\(-\dfrac{3}{7}+\dfrac{5}{13}+\dfrac{-4}{12}=-\dfrac{103}{273}\)

b.\(-\dfrac{5}{21}+\dfrac{-2}{21}+\dfrac{8}{24}=\dfrac{-5-2}{21}+\dfrac{8}{24}=-\dfrac{7}{21}+\dfrac{8}{24}=-\dfrac{1}{3}+\dfrac{8}{24}=0\)

c.\(\dfrac{5}{13}+\dfrac{-5}{7}+\dfrac{-20}{41}+\dfrac{8}{13}+\dfrac{-21}{41}=\left(\dfrac{5}{13}+\dfrac{8}{13}\right)+\left(\dfrac{-20}{41}+\dfrac{-21}{41}\right)+-\dfrac{5}{7}=1-1-\dfrac{5}{7}=-\dfrac{5}{7}\)

\(-\dfrac{5}{7}\left(\dfrac{-19}{41}+-\dfrac{21}{41}+1\right)=-\dfrac{5}{7}.\dfrac{1}{41}=-\dfrac{5}{287}\)

\(=\dfrac{-5}{7}\left(\dfrac{19}{41}+\dfrac{21}{41}-1\right)=\dfrac{-5}{7}\cdot\dfrac{-1}{41}=\dfrac{5}{287}\)

khó nhìn quá e chỉnh lại đi nha

A.-9/2

b.-5/7

C.5/287

D.302/105

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