DẤU / LÀ PHẦN NHÉ 

a, \(\dfrac{20}{15}=\dfrac{4}{3}\)

b, \(\dfrac{6}{15}=\dfrac{2}{5}\)

c, \(\dfrac{42}{30}=\dfrac{7}{5}\)

d, \(\dfrac{40}{35}=\dfrac{8}{7}\)

e, \(\dfrac{42}{42}=1\)

g, \(\dfrac{54}{10}=\dfrac{27}{5}\)

h, \(\dfrac{12}{15}\)

k đúng để nhận câu trả lời
 

    \(\dfrac{7}{6}\) + \(\dfrac{5}{12}\) - \(\dfrac{1}{18}\) - 1 

=  \(\dfrac{42}{36}\) + \(\dfrac{15}{36}\) - \(\dfrac{2}{36}\) - \(\dfrac{36}{36}\)

= \(\dfrac{19}{36}\)

\(\dfrac{13}{6}\) + \(\dfrac{5}{18}+3-\dfrac{7}{12}\)

= \(\dfrac{78}{36}+\dfrac{10}{36}+\dfrac{108}{36}-\dfrac{21}{36}\)

= \(\dfrac{175}{36}\)

3 + \(\dfrac{11}{4}-\dfrac{1}{12}-\dfrac{3}{16}\)

= \(\dfrac{144}{48}+\dfrac{132}{48}-\dfrac{4}{48}-\dfrac{9}{48}\)

= \(\dfrac{263}{48}\)

   \(\dfrac{2}{5}\) x \(\dfrac{7}{4}\) - \(\dfrac{2}{5}\) x \(\dfrac{3}{4}\)

=  \(\dfrac{2}{5}\) x ( \(\dfrac{7}{4}\) - \(\dfrac{3}{4}\))

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

= \(\dfrac{2}{5}\)

đầy đủ phần ngoặc hay gì đó

\(\dfrac{11}{2}\): \(\dfrac{1}{4}\) \(\times\) \(\dfrac{5}{3}\)

= \(\dfrac{11}{2}\) \(\times\) \(\dfrac{4}{1}\) \(\times\) \(\dfrac{5}{3}\)

= 22 \(\times\) \(\dfrac{5}{3}\)

= \(\dfrac{110}{3}\)

\(\dfrac{5}{2}-\dfrac{1}{4}+\dfrac{5}{3}\)

= \(\dfrac{30}{12}-\dfrac{3}{12}+\dfrac{20}{12}\)

= \(\dfrac{7}{12}\) 

\(\dfrac{14}{5}\times\dfrac{2}{3}\)+ 5

= \(\dfrac{28}{15}\) + 5

= \(\dfrac{28}{15}\) + \(\dfrac{75}{15}\)

= \(\dfrac{103}{15}\)

\(\left(\dfrac{6}{11}+\dfrac{5}{11}\right)\times\dfrac{3}{7}=\dfrac{11}{11}\times\dfrac{3}{7}=1\times\dfrac{3}{7}=\dfrac{3}{7}\)

\(\dfrac{3}{5}\left(\dfrac{7}{9}-\dfrac{2}{9}\right)=\dfrac{3}{5}\times\dfrac{5}{9}=\dfrac{1}{3}\)

`( 6 / 11 + 5 / 11 ) xx 3 / 7 = 11 / 11 xx 3 / 7 = 1 xx 3 / 7 = 3 / 7`

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`3 / 5 xx 7 / 9 - 3 / 5 xx 2 / 9 = 3 / 5 xx ( 7 / 9 - 2 / 9 ) = 3 / 5 xx 5 / 9 = 1 / 3`