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a)
\(\begin{array}{l}\frac{2}{3} + \frac{{ - 2}}{5} + \frac{{ - 5}}{6} - \frac{{13}}{{10}}\\ = \frac{2}{3} + \frac{{ - 5}}{6} + \frac{{ - 2}}{5} - \frac{{13}}{{10}}\\ = \left( {\frac{2}{3} + \frac{{ - 5}}{6}} \right) + \left( {\frac{{ - 2}}{5} - \frac{{13}}{{10}}} \right)\\ = \left( {\frac{4}{6} + \frac{{ - 5}}{6}} \right) + \left( {\frac{{ - 4}}{{10}} - \frac{{13}}{{10}}} \right)\\ = \frac{{ - 1}}{6} + \frac{{ - 17}}{{10}}\\ = \frac{{ - 5}}{{30}} + \frac{{ - 51}}{{30}}\\ = \frac{{ - 56}}{{30}}\\ = \frac{{ - 28}}{{15}}\end{array}\)
b)
\(\begin{array}{l}\frac{{ - 3}}{7}.\frac{{ - 1}}{9} + \frac{7}{{ - 18}}.\frac{{ - 3}}{7} + \frac{5}{6}.\frac{{ - 3}}{7}\\ = \frac{{ - 3}}{7}.\left( {\frac{{ - 1}}{9} + \frac{7}{{ - 18}} + \frac{5}{6}} \right)\\ = \frac{{ - 3}}{7}.\left( {\frac{{ - 2}}{{18}} + \frac{{ - 7}}{{18}} + \frac{{15}}{{18}}} \right)\\ = \frac{{ - 3}}{7}.\frac{{ 6}}{{18}}\\ = \frac{-1}{7}\end{array}\).
M = 3/4 - 3/5 + 3/7 + 3/11 / 13/4 - 13/5 + 13/7 + 13/11
M = 3.(1/4 - 1/5 + 1/7 + 1/11) / 13.(1/4 - 1/5 + 1/7 + 1/11)
M = 3/13
M = 3/4 - 3/5 + 3/7 + 3/11 / 13/4 - 13/5 + 13/7 + 13/11
M = 3.(1/4 - 1/5 + 1/7 + 1/11) / 13.(1/4 - 1/5 + 1/7 + 1/11)
M = 3/13
\(A\)\(=\)\(\frac{1}{9}\)\(-\)\(\frac{1}{10}\)\(+\)\(\frac{1}{10}\)\(-\)\(\frac{1}{11}\)\(+\)\(\frac{1}{11}\)\(-\)\(\frac{1}{12}\)\(+\)\(\frac{1}{12}\)\(-\)\(\frac{1}{13}\)\(+\)\(\frac{1}{13}\)\(-\)\(\frac{1}{14}\)\(+\)\(\frac{1}{14}\)\(-\)\(\frac{1}{15}\)
\(A\)\(=\)\(\frac{1}{9}\)\(-\)\(\frac{1}{15}\)
\(A\)\(=\)\(\frac{2}{45}\)
\(A=\left(\frac{1}{9}.\frac{1}{10}+\frac{1}{10}.\frac{1}{11}\right)+\left(\frac{1}{11}.\frac{1}{12}+\frac{1}{12}.\frac{1}{13}\right)+\left(\frac{1}{13}.\frac{1}{14}+\frac{1}{14}.\frac{1}{15}\right)\)
Sau đó nhân phân phối ra là xong nhé bạn
\(=\frac{4+9}{4.9}-\frac{14-9}{9.14}-\frac{14+19}{14.19}+\frac{19+24}{19.24}\)
\(=\frac{4}{4.9}+\frac{9}{4.9}-\frac{14}{9.14}-\frac{9}{9.14}-\frac{14}{14.19}+\frac{19}{14.19}+\frac{19}{19.24}+\frac{24}{19.24}\)
\(\frac{1}{9}+\frac{1}{4}-\frac{1}{9}-\frac{1}{14}-\frac{1}{19}+\frac{1}{14}+\frac{1}{19}+\frac{1}{24}\)
\(=\frac{1}{4}+\frac{1}{24}=\frac{7}{24}\)
AI THẤY ĐÚNG ỦNG HỘ NHA
A= \(49\frac{8}{23}-\left(5\frac{7}{32}+14\frac{8}{23}\right)\)
=\(\frac{1135}{32}-\left(\frac{167}{32}+\frac{330}{23}\right)\)
=\(\frac{1135}{23}-\frac{167}{32}-\frac{330}{23}\)
=\(\left(\frac{1135}{23}-\frac{330}{23}\right)-\frac{167}{32}\)
=\(\frac{805}{23}-\frac{167}{32}\)
=\(\frac{953}{32}\)
1/13. 8/13 - 14/13 + 5/13 .1/13
= 1/13. ( 8/13+5/13) -14/13
= 1/13. 13/13-14/13
= 1/13 . 1 - 14/13
= 1/13-14/13
= -13/13
= -1
k cho mik nhoa
1/13. 8/13 - 14/13 + 5/13 .1/13
= 1/13. ( 8/13+5/13) -14/13
= 1/13. 13/13-14/13
= 1/13 . 1 - 14/13
= 1/13-14/13
= -13/13
= -1