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Bài 2:
a: \(=248+2064-12-236\)
\(=12-12+2064=2064\)
b: \(=-298-302-300=-600-300=-900\)
c: \(=5-7+9-11+13-15=-2-2-2=-6\)
d: \(=456+58-456-38=20\)
a: \(=\dfrac{-3}{7}\left(\dfrac{5}{9}+\dfrac{4}{9}\right)+2+\dfrac{3}{7}=2\)
b: \(=-\dfrac{5}{7}:\left(24-\dfrac{166}{7}\right)+\dfrac{37}{3}\)
\(=-\dfrac{5}{7}:\dfrac{2}{7}+\dfrac{37}{3}=\dfrac{-5}{2}+\dfrac{37}{3}=\dfrac{59}{6}\)
c: \(=4-\dfrac{32}{27}\cdot\dfrac{-27}{8}=4+4=8\)
d: \(=\dfrac{28}{15}\cdot\dfrac{3}{4}-\dfrac{11+5}{20}\cdot\dfrac{5}{7}\)
\(=\dfrac{7}{5}-\dfrac{6}{20}\cdot\dfrac{5}{7}=\dfrac{29}{35}\)
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: \(=\dfrac{2}{7}\left(\dfrac{21}{4}-\dfrac{13}{4}\right)=\dfrac{4}{7}\)
Câu 1:
a: =(1+2-3-4)+(5+6-7-8)+...+(2013+2014-2015-2016)
=(-4)+(-4)+...+(-4)
=-4x504=-2016
b: \(B=\dfrac{3}{4}\cdot\dfrac{8}{9}\cdot...\cdot\dfrac{195}{196}=\dfrac{1\cdot3\cdot2\cdot4\cdot...\cdot13\cdot15}{2\cdot3\cdot...\cdot14\cdot2\cdot3\cdot...\cdot14}=\dfrac{15}{14\cdot2}=\dfrac{15}{28}\)