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. Tham khảo nha !!!
\(\frac{16}{15.31}+\frac{14}{31.45}+\frac{7}{45.52}+\frac{7}{52.65}+\frac{1}{13.70}\)
\(=\frac{16}{15.31}+\frac{14}{31.45}+\frac{7}{45.52}+\frac{7}{52.65}+\frac{5}{65.70}\)
\(=\frac{1}{15}-\frac{1}{31}+\frac{1}{31}-\frac{1}{45}+\frac{1}{45}-\frac{1}{52}+\frac{1}{52}-\frac{1}{65}+\frac{1}{65}-\frac{1}{70}\)
\(=\frac{1}{15}-\frac{1}{70}\)
\(=\frac{70}{1050}-\frac{15}{1050}\)
\(=\frac{55}{1050}\)
\(=\frac{11}{210}\)
Chúc bạn học tốt !!!
= 1/15 - 1/31 + 1/31 - 1/45 + 1/45 - 1/52 + 1/52 - 1/65 + 1/13.70
= 1/15 - 1/65 + 1/13.70
= 2/39 + 1/910
= 11/210
Tk mk nha
\(\frac{16}{15.31}+\frac{14}{31.45}+\frac{7}{45.52}+\frac{13}{52.65}+\frac{1}{13.70}\)
\(=\frac{16}{15.31}+\frac{14}{31.45}+\frac{7}{45.52}+\frac{13}{52.65}+\frac{5}{65.70}\)
\(=\frac{1}{15}-\frac{1}{31}+\frac{1}{31}-\frac{1}{45}+\frac{1}{45}-\frac{1}{52}+\frac{1}{52}-\frac{1}{65}+\frac{1}{65}-\frac{1}{70}=\frac{1}{15}-\frac{1}{70}=\frac{11}{210}\)
Lời giải:
$A=\frac{15-5}{5.15}+\frac{31-15}{15.31}+\frac{45-31}{31.45}+\frac{52-45}{45.52}+\frac{65-52}{52.65}+\frac{1}{13.70}+\frac{1}{70.15}$
$=\frac{1}{5}-\frac{1}{15}+\frac{1}{15}-\frac{1}{31}+\frac{1}{31}-\frac{1}{45}+\frac{1}{45}-\frac{1}{52}+\frac{1}{52}-\frac{1}{65}+\frac{1}{70}(\frac{1}{13}+\frac{1}{15})$
$=\frac{1}{5}-\frac{1}{65}+\frac{1}{70}.\frac{28}{195}$
$=\frac{12}{65}+\frac{2}{95}$
$=\frac{254}{1325}$
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)
\(\begin{array}{l}\frac{{ - 3}}{7}.\frac{{ - 1}}{9} + \frac{7}{{ - 18}}.\frac{{ - 3}}{7} + \frac{5}{6}.\frac{{ - 3}}{7}\\ = \frac{{ - 3}}{7}.\left( {\frac{{ - 1}}{9} + \frac{7}{{ - 18}} + \frac{5}{6}} \right)\\ = \frac{{ - 3}}{7}.\left( {\frac{{ - 2}}{{18}} + \frac{{ - 7}}{{18}} + \frac{{15}}{{18}}} \right)\\ = \frac{{ - 3}}{7}.\frac{{ 6}}{{18}}\\ = \frac{-1}{7}\end{array}\).
\(A\)\(=\)\(\frac{1}{9}\)\(-\)\(\frac{1}{10}\)\(+\)\(\frac{1}{10}\)\(-\)\(\frac{1}{11}\)\(+\)\(\frac{1}{11}\)\(-\)\(\frac{1}{12}\)\(+\)\(\frac{1}{12}\)\(-\)\(\frac{1}{13}\)\(+\)\(\frac{1}{13}\)\(-\)\(\frac{1}{14}\)\(+\)\(\frac{1}{14}\)\(-\)\(\frac{1}{15}\)
\(A\)\(=\)\(\frac{1}{9}\)\(-\)\(\frac{1}{15}\)
\(A\)\(=\)\(\frac{2}{45}\)
\(A=\left(\frac{1}{9}.\frac{1}{10}+\frac{1}{10}.\frac{1}{11}\right)+\left(\frac{1}{11}.\frac{1}{12}+\frac{1}{12}.\frac{1}{13}\right)+\left(\frac{1}{13}.\frac{1}{14}+\frac{1}{14}.\frac{1}{15}\right)\)
Sau đó nhân phân phối ra là xong nhé bạn
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
37/663
giúp mk đi, mai mk nộp rùi đó