\(\dfrac{12}{-17}-\dfrac{8}{16}\) Lười lm qá...=((
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a: \(=\dfrac{8}{9}\cdot\dfrac{9}{4}\cdot\dfrac{12}{19}\cdot\dfrac{19}{24}=\dfrac{1}{2}\cdot2=1\)
b: \(=\dfrac{5}{16}\cdot\dfrac{17}{15}\cdot\dfrac{8}{17}=\dfrac{5}{16}\cdot\dfrac{8}{15}=\dfrac{40}{240}=\dfrac{1}{6}\)
c: \(=\dfrac{4}{13}\left(\dfrac{2}{7}+\dfrac{5}{7}\right)-\dfrac{3}{26}=\dfrac{4}{13}-\dfrac{3}{26}=\dfrac{5}{26}\)
c: \(=\dfrac{3}{4}\left(\dfrac{6}{11}+\dfrac{5}{11}\right)-\dfrac{1}{5}=\dfrac{3}{4}-\dfrac{1}{5}=\dfrac{11}{20}\)
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a, 1. \(\dfrac{2}{17}\)
2. \(22\)
3. 4
b,
1. \(\dfrac{8}{5}\)
2. \(\dfrac{176}{5}\)
3. \(\dfrac{28}{5}\)
4. \(\dfrac{3}{10}\)
5. \(\dfrac{163}{5}\)
6. \(\dfrac{9}{20}\)
a) \(\dfrac{12}{17}:6=\dfrac{12}{17}\cdot\dfrac{1}{6}=\dfrac{2}{17}\)
a: 3/8=36/96
5/12=40/96
b: -2/9=-24/108
-5/12=-45/108
c: -3/16=-63/336
-5/24=-70/336
-21/56=-126/336
\(PTK_{^{65}Cu^{16}O}=65+16=81\left(đ.v.C\right)\\ PTK_{^{65}Cu^{17}O}=65+17=82\left(đ.v.C\right)\\ PTK_{^{65}Cu^{18}O}=65+18=83\left(đ.v.C\right)\\ PTK_{^{63}Cu^{16}O}=63+16=79\left(đ.v.C\right)\\ PTK_{^{63}Cu^{17}O}=63+17=80\left(đ.v.C\right)\\ PTK_{^{63}Cu^{18}O}=63+18=81\left(đ.v.C\right)\)
a) Ta có: \(\dfrac{5}{8}+\dfrac{3}{17}+\dfrac{4}{18}+\dfrac{20}{-17}+\dfrac{-2}{9}+\dfrac{21}{56}\)
\(=\left(\dfrac{3}{17}-\dfrac{20}{17}\right)+\left(\dfrac{2}{9}-\dfrac{2}{9}\right)+\left(\dfrac{5}{8}+\dfrac{3}{8}\right)\)
\(=-1+1=0\)
b) Ta có: \(\left(\dfrac{9}{16}+\dfrac{8}{-27}\right)+\left(1+\dfrac{7}{16}+\dfrac{-19}{27}\right)\)
\(=\left(\dfrac{9}{16}+\dfrac{7}{16}\right)+\left(\dfrac{-8}{27}-\dfrac{19}{27}\right)+1\)
=1-1+1=1
`12/[-17]-8/16=[-192]/272-136/272=-328/272=-41/34`
`12/(-17)-8/16`
`=-12/17-1/2`
`=-24/34 -17/34`
`=-41/34`