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a) \(\dfrac{7}{30}+\dfrac{\left(-12\right)}{37}+\dfrac{23}{30}+\dfrac{\left(-25\right)}{37}=\left(\dfrac{7}{30}+\dfrac{23}{30}\right)+\left(\dfrac{-12}{37}+\dfrac{-25}{37}\right)=1+\left(-1\right)=0\)
b) \(\dfrac{5}{7}\cdot\dfrac{5}{11}+\dfrac{5}{7}\cdot\dfrac{2}{11}-\dfrac{5}{7}\cdot\dfrac{14}{11}=\dfrac{5}{7}\cdot\left(\dfrac{5}{11}+\dfrac{2}{11}-\dfrac{14}{11}\right)=\dfrac{5}{7}\cdot\left(-\dfrac{7}{11}\right)=-\dfrac{5}{11}\)
c) \(\dfrac{\left(-5\right)}{7}\cdot\dfrac{3}{13}-\dfrac{5}{7}\cdot\dfrac{10}{13}+1\dfrac{5}{7}=\dfrac{5}{7}\cdot\dfrac{-3}{13}-\dfrac{5}{7}\cdot\dfrac{10}{13}+\dfrac{12}{7}=\dfrac{5}{7}\cdot\left(\dfrac{-3}{13}-\dfrac{10}{13}\right)+\dfrac{12}{7}=\dfrac{5}{7}\cdot\left(-1\right)+\dfrac{12}{7}=\left(-\dfrac{5}{7}\right)+\dfrac{12}{7}=\dfrac{7}{7}=1\)
a; - \(\dfrac{10}{13}\) + \(\dfrac{5}{17}\) - \(\dfrac{3}{13}\) + \(\dfrac{12}{17}\) - \(\dfrac{11}{20}\)
= - (\(\dfrac{10}{13}\) + \(\dfrac{3}{13}\)) + (\(\dfrac{5}{17}\) + \(\dfrac{12}{17}\)) - \(\dfrac{11}{20}\)
= - 1 + 1 - \(\dfrac{11}{20}\)
= 0 - \(\dfrac{11}{20}\)
= - \(\dfrac{11}{20}\)
b; \(\dfrac{3}{4}\) + \(\dfrac{-5}{6}\) - \(\dfrac{11}{-12}\)
= \(\dfrac{9}{12}\) - \(\dfrac{10}{12}\) + \(\dfrac{11}{12}\)
= \(\dfrac{10}{12}\)
= \(\dfrac{5}{6}\)
c; [13.\(\dfrac{4}{9}\) + 2.\(\dfrac{1}{9}\)] - 3.\(\dfrac{4}{9}\)
= [\(\dfrac{52}{9}\) + \(\dfrac{2}{9}\)] - \(\dfrac{4}{3}\)
= \(\dfrac{54}{9}\) - \(\dfrac{4}{3}\)
= \(\dfrac{14}{3}\)
\(\frac{5}{6}\cdot\left(-\frac{2}{3}\right)+\frac{1}{4}\)
\(=-\frac{5}{9}+\frac{1}{4}\)
\(=-\frac{11}{36}\)
\(1\frac{11}{12}-\frac{5}{12}\left(\frac{4}{5}-\frac{1}{10}\right):\left(-\frac{5}{12}\right)\)
\(=\frac{23}{12}-\frac{5}{12}\cdot\frac{7}{10}:\left(-\frac{5}{12}\right)\)
\(=\frac{23}{12}-\frac{7}{24}:\left(-\frac{5}{12}\right)\)
\(=\frac{23}{12}-\)\(\left(-\frac{7}{10}\right)\)
\(=\frac{157}{60}\)
b/1.2.3.....2013 - 1.2.3....2012-1.2.3...20122
= (1.2.3...2012.2013-1.2.3...2012)-1.2.3...2012.2012
= 1.2.3...2012(2013-1-2012)
=1.2.3...2012.0=0
`Answer:`
a. \(-\frac{17}{30}-\frac{11}{-15}+-\frac{7}{12}\)
\(=-\frac{17}{30}+\frac{11}{15}-\frac{7}{12}\)
\(=-\frac{17}{30}+\frac{22}{30}-\frac{7}{12}\)
\(=\frac{1}{6}-\frac{7}{12}\)
\(=-\frac{5}{12}\)
b. \(-\frac{5}{9}+\frac{5}{9}:\left(\frac{5}{3}-\frac{25}{12}\right)\)
\(=-\frac{5}{9}+\frac{5}{9}:\left(-\frac{5}{12}\right)\)
\(=\frac{5}{9}.\left(-1\right)+\frac{5}{9}.\left(-\frac{12}{5}\right)\)
\(=\frac{5}{9}.\left(-1-\frac{12}{5}\right)\)
\(=\frac{5}{9}.\frac{-17}{5}\)
\(=-\frac{17}{9}\)
c. \(-\frac{7}{25}.\frac{11}{13}+-\frac{7}{25}-\frac{2}{13}-\frac{18}{25}\)
\(=\frac{77}{325}-\left(\frac{7}{25}+\frac{18}{25}\right)-\frac{2}{13}\)
\(=\frac{77}{325}-1-\frac{2}{13}\)
\(=-\frac{452}{325}\)
b: =12+5/14-3-5/7-5-5/14
=4-5/7
=28/7-5/7=23/7
c: =(-2/5-11/10)+(7/11-7/11)
=-4/10-11/10=-15/10=-3/2
\(a,\dfrac{5}{9}\cdot\dfrac{7}{13}+\dfrac{5}{9}\cdot\dfrac{8}{13}-\dfrac{5}{13}\cdot\dfrac{2}{9}\)
\(=\dfrac{5}{9}\cdot\dfrac{7}{13}+\dfrac{5}{9}\cdot\dfrac{8}{13}-\dfrac{2}{13}\cdot\dfrac{5}{9}\)
\(=\dfrac{5}{9}\cdot\left(\dfrac{7}{13}+\dfrac{8}{13}-\dfrac{2}{13}\right)\)
\(=\dfrac{5}{9}\cdot\dfrac{14}{13}\)
\(=\dfrac{70}{117}\)
\(d,\dfrac{1}{2}+\dfrac{-2}{3}+\dfrac{1}{6}+\dfrac{-2}{5}\)
\(=\left(\dfrac{1}{2}+\dfrac{-2}{3}+\dfrac{1}{6}\right)+\dfrac{-2}{5}\)
\(=0+\dfrac{-2}{5}\)
\(=\dfrac{-2}{5}\)
13 - 12 + 11 - 10 - 9 + 8 - 7 - 6 + 5 - 4 + 3 + 2 - 1
= ( 13 - 12 + 11 - 10 + 8 ) - ( 9 + 1 ) - ( 6 + 4) + ( 3 + 2 + 5 ) - 7
= 10 - 10 - 10 + 10 - 7
= ( 10 - 10 ) - ( 10 - 10 ) - 7
= 0 - 0 - 7
= - 7
=5^39/5^33
=5^6
=15625
bằng 25
tui là người đầu tiên nhớ cho nhiều h nhé