d) 

` (-3)/7 + 5/13 + (-4)/7 =   -3/7 + (-4/7 )  + 5/13 = -1 + 5/13 = -8/13`

e2) 

`-5/21 + (-2)/21 + (-8)/4 = -7/21 + -8/4 = -7/3`

a) \(\frac{58}{19}+\frac{13}{17}+\frac{35}{43}+\frac{119}{19}+\frac{8}{43}\)

\(=\frac{13}{17}+\left(\frac{58}{19}+\frac{119}{19}\right)+\left(\frac{35}{43}+\frac{8}{43}\right)\)

\(=\frac{13}{17}+\frac{204}{19}+1\)

\(=\frac{1808}{133}\)

b) \(\frac{-5}{7}.\frac{2}{11}+\frac{-5}{7}.\frac{9}{11}+\frac{13}{4}\)

\(=\frac{-5}{7}.\left(\frac{2}{11}+\frac{9}{11}\right)+\frac{13}{4}\)

\(=\frac{-5}{7}.1+\frac{13}{4}\)

\(=\frac{71}{28}\)

c) \(\frac{146}{13}-\left(\frac{21}{7}+\frac{68}{13}\right)\)

\(=\left(\frac{164}{13}-\frac{68}{13}\right)+3\)

\(=\frac{135}{13}\)

d) \(\frac{2}{7}.\frac{21}{4}-\frac{2}{7}.\frac{13}{4}\)

\(=\frac{2}{7}.\left(\frac{21}{4}-\frac{13}{4}\right)\)

\(=\frac{2}{7}.\frac{8}{4}\)

\(=\frac{4}{7}\)

P/s: Mk ko chắc nữa!

b: \(=\dfrac{-5}{7}\left(\dfrac{2}{11}+\dfrac{9}{11}\right)+\dfrac{13}{4}=\dfrac{-5}{7}+\dfrac{13}{4}=\dfrac{-20+91}{28}=\dfrac{71}{28}\)

c: \(=\dfrac{146}{13}-3-\dfrac{68}{13}=6-3=3\)

d: \(=\dfrac{2}{7}\left(\dfrac{21}{4}-\dfrac{13}{4}\right)=\dfrac{4}{7}\)

cách 1:5/7 x 13/21 +2/7 x 13/21

=65/147 + 26/147

=13/21

cách 2:5/7 x 13/21+2/7 x 13/21

=13/21 nha

=

5/4

\(\dfrac{4}{7}-\dfrac{4}{7}+\dfrac{8}{21}+\dfrac{13}{21}+\left(-\dfrac{1}{2}\right)^2=\dfrac{1}{4}\)

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

\(\dfrac{26}{81}+\dfrac{4}{27}=\dfrac{26+12}{81}=\dfrac{38}{81}\)

\(\dfrac{5}{64}+\dfrac{7}{8}=\dfrac{5+56}{64}=\dfrac{61}{64}\)

\(\dfrac{26}{81}+\dfrac{4}{27}=\dfrac{26}{81}+\dfrac{4\times3}{27\times3}=\dfrac{26}{81}+\dfrac{12}{81}=\dfrac{38}{81}\)

\(\dfrac{5}{64}+\dfrac{7}{8}=\dfrac{5}{64}+\dfrac{7\times8}{8\times8}=\dfrac{5}{64}+\dfrac{56}{64}=\dfrac{61}{64}\)

( \(\dfrac{1}{2}\) - \(\dfrac{13}{14}\)): \(\dfrac{5}{7}\) - (- \(\dfrac{2}{21}\) + \(\dfrac{1}{7}\)) : \(\dfrac{5}{7}\)

(\(\dfrac{7}{14}\) - \(\dfrac{13}{14}\)): \(\dfrac{5}{7}\) - ( - \(\dfrac{2}{21}\) + \(\dfrac{3}{21}\)): \(\dfrac{5}{7}\)

- \(\dfrac{6}{14}\): \(\dfrac{5}{7}\)  - \(\dfrac{1}{21}\): \(\dfrac{5}{7}\)

= - (\(\dfrac{3}{7}\) + \(\dfrac{1}{21}\)): \(\dfrac{5}{7}\)

= -\(\dfrac{10}{21}\): \(\dfrac{5}{7}\)

= - \(\dfrac{2}{3}\)