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1: \(=\dfrac{16}{15}\left(-\dfrac{4}{9}+\dfrac{3}{7}\right)+\dfrac{16}{15}\left(\dfrac{4}{7}-\dfrac{5}{9}\right)\)
\(=\dfrac{16}{15}\left(-\dfrac{4}{9}+\dfrac{3}{7}+\dfrac{4}{7}-\dfrac{5}{9}\right)=0\)
2: \(=\dfrac{29}{9}\left(15+\dfrac{4}{7}-8-\dfrac{1}{7}+\dfrac{15}{7}-\dfrac{1}{7}\right)\)
\(=\dfrac{20}{9}\cdot\left(7\cdot\dfrac{18}{7}\right)=\dfrac{20}{9}\cdot18=40\)
1: \(=-\dfrac{7}{80}\cdot\dfrac{4}{7}-\dfrac{2}{9}:\dfrac{16}{3}+\dfrac{5}{24}\cdot\left(\dfrac{-50+38}{15}\right)^2\)
\(=\dfrac{-1}{20}-\dfrac{2}{9}\cdot\dfrac{3}{16}+\dfrac{5}{24}\cdot\dfrac{16}{25}\)
\(=\dfrac{-1}{20}-\dfrac{1}{24}+\dfrac{2}{15}\)
\(=\dfrac{-6-5+16}{120}=\dfrac{5}{120}=\dfrac{1}{24}\)
2: \(=1500-\left\{10^3-11\cdot\left[49-5\cdot8\right]\right\}\)
\(=1500-\left\{1000-11\cdot9\right\}\)
\(=1500-1000+99=599\)
\(\dfrac{4}{7}.\dfrac{89}{5}-\dfrac{4}{5}.\dfrac{82}{7}\)
\(=\dfrac{4}{7}.\dfrac{89}{5}-\dfrac{4}{7}.\dfrac{82}{5}\)
\(=\dfrac{4}{7}.\left(\dfrac{89}{5}-\dfrac{82}{5}\right)\)
\(=\dfrac{4}{7}.\dfrac{7}{5}\)
\(=\dfrac{4}{5}\)
\(\dfrac{5}{7}.\dfrac{-4}{19}+\dfrac{-15}{7}.\dfrac{5}{19}\)
\(=\dfrac{5}{7}.\dfrac{-4}{19}+\dfrac{5}{7}.\dfrac{-15}{19}\)
\(=\dfrac{5}{7}.\left(\dfrac{-4}{19}+\dfrac{-15}{19}\right)\)
\(=\dfrac{5}{7}.\left(-1\right)\)
\(=\dfrac{-5}{7}\)
\(-2\dfrac{1}{4}.\)\(\left(3\dfrac{5}{12}-1\dfrac{2}{9}\right)\)
=\(\dfrac{-9}{4}\).\(\left(\dfrac{41}{12}-\dfrac{11}{9}\right)\)
=\(\dfrac{-9}{4}.\dfrac{41}{12}-\dfrac{-9}{4}.\dfrac{11}{9}\)
=\(\dfrac{-123}{16}-\dfrac{-11}{4}\)
=\(\dfrac{-123}{16}-\dfrac{-44}{16}\)
=\(\dfrac{-79}{16}\)
\(\left(-25\%+0,75+\dfrac{7}{12}\right)\div\left(-2\dfrac{1}{8}\right)\)
=\(\left(\dfrac{-1}{4}+\dfrac{3}{4}+\dfrac{7}{12}\right)\div\left(\dfrac{-17}{8}\right)\)
=\(\left(\dfrac{-3}{12}+\dfrac{9}{12}+\dfrac{7}{12}\right).\dfrac{-8}{17}\)
=\(\dfrac{13}{12}.\dfrac{-8}{17}=\dfrac{-26}{51}\)
\(3\dfrac{1}{2}+15\dfrac{4}{9}:\dfrac{26}{7}-2\dfrac{4}{9}:\dfrac{26}{7}\)
\(=\dfrac{7}{2}+\dfrac{139}{9}:\dfrac{26}{7}-\dfrac{22}{9}:\dfrac{26}{7}\)
\(=\dfrac{7}{2}+\left(\dfrac{139}{9}-\dfrac{22}{9}\right):\dfrac{26}{7}\)
\(=\dfrac{7}{2}+13:\dfrac{26}{7}\)
\(=\dfrac{7}{2}+\dfrac{7}{2}\)
\(=7.\)
\(3\dfrac{1}{2}+15\dfrac{4}{9}:\dfrac{26}{7}-2\dfrac{4}{9}:\dfrac{26}{7}\)
=\(\dfrac{7}{2}+\dfrac{139}{9}:\dfrac{26}{7}-\dfrac{22}{9}:\dfrac{26}{7}\)
=\(\dfrac{7}{2}+\left(\dfrac{139}{9}-\dfrac{22}{9}\right):\dfrac{26}{7}\)
=\(\dfrac{7}{2}+13:\dfrac{26}{7}\)
=\(\dfrac{7}{2}+13.\dfrac{7}{26}\)
=\(\dfrac{7}{2}+\dfrac{7}{2}\)
= 7
2)
\(2+\dfrac{5}{7}+\left(\dfrac{\dfrac{3}{19}+\dfrac{3}{23}-\dfrac{3}{28}}{\dfrac{5}{19}+\dfrac{5}{23}-\dfrac{5}{28}}\right)\cdot x=\dfrac{20}{7}\\ \left[\dfrac{3\cdot\left(\dfrac{1}{19}+\dfrac{1}{23}-\dfrac{1}{28}\right)}{5\cdot\left(\dfrac{1}{19}+\dfrac{1}{23}-\dfrac{1}{28}\right)}\right]\cdot x=\dfrac{20}{7}-\dfrac{5}{7}-2\\ \dfrac{3}{5}x=\dfrac{15}{7}-2\\ \dfrac{3}{5}x=\dfrac{1}{7}\\ x=\dfrac{5}{21}\)
c,
= \(\dfrac{5}{9}.\left(\dfrac{7}{13}+\dfrac{9}{13}+\dfrac{-3}{13}\right)\)
= \(\dfrac{5}{9}.1\)
= \(\dfrac{5}{9}\)
\(\dfrac{1}{6}.x+\dfrac{1}{10}.x-\dfrac{4}{15}.x+1=0\)
=> \(\left(\dfrac{1}{6}+\dfrac{1}{10}-\dfrac{4}{15}\right).x+1\)= 0
=> \(0.x+1=0\)
=> 0 . x = 0 - 1
=> 0 . x = -1
=> x = 0 : -1
=> x = 0
~ Chúc bạn học giỏi ! ~
\(\dfrac{1}{6}x+\dfrac{1}{10}x-\dfrac{4}{15}x+1=0\)
\(\Leftrightarrow\left(\dfrac{1}{6}+\dfrac{1}{10}-\dfrac{4}{15}\right)x+1=0\)
\(\Leftrightarrow0x+1=0\)\(\)
Vì 0x luôn = 0 => 0x + 1 > 0
<=> x \(\in\varnothing\)
\(\dfrac{5}{7} *\dfrac{-4}{19}-\dfrac{5*2}{7}*\dfrac{15}{19*2} =\dfrac{5}{7}*(\dfrac{-4}{19}-\dfrac{15}{19}) =\dfrac{5}{7}*(\dfrac{-19}{19})=\dfrac{-5}{7}\)