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Bài làm:
a) \(\left(\frac{2x}{7}-5\right)\div\left(-8\right)=0,75\)
\(\Leftrightarrow\frac{2x}{7}-5=-6\)
\(\Leftrightarrow\frac{2x}{7}=-1\)
\(\Leftrightarrow x=-\frac{7}{2}\)
b) \(\frac{11}{13}-\left(\frac{5}{42}-x\right)=-\left(\frac{15}{28}-\frac{11}{13}\right)\)
\(\Leftrightarrow x+\frac{11}{13}-\frac{5}{42}=\frac{11}{13}-\frac{15}{28}\)
\(\Rightarrow x=-\frac{5}{7}\)
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\(1\frac{13}{15}.0,75-\left(\frac{11}{20}+\frac{25}{100}\right):\frac{7}{5}\)
\(=\frac{28}{15}.\frac{3}{4}-\frac{4}{5}:\frac{7}{5}\)
\(=\frac{7}{5}-\frac{4}{7}\)
\(=\frac{29}{35}\)
\(1\frac{13}{15}\cdot0,75-\left(\frac{11}{20}+\frac{25}{100}\right):\frac{7}{5}\)
\(=\frac{28}{15}\cdot\frac{3}{4}-\frac{4}{5}:\frac{7}{5}\)
\(=\frac{7}{5}-\frac{4}{7}\)
\(=\frac{29}{35}\)
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\(1\frac{13}{15}.0,75-\left(\frac{11}{20}+25\%\right):\frac{7}{3}\)
\(=\frac{28}{15}.\frac{3}{4}-\left(\frac{11}{20}+\frac{1}{4}\right):\frac{7}{3}\)
\(=\frac{7}{5}-\frac{4}{5}.\frac{3}{7}\)
\(=\frac{7}{5}-\frac{12}{35}\)
\(=\frac{37}{35}\)
Đặt A=\(1\frac{13}{15}\). \(0,75\) - (\(\frac{11}{20}\)+25%):\(\frac{7}{3}\)
A=\(\frac{28}{15}\). \(\frac{3}{4}\)-(\(\frac{11}{20}\)+\(\frac{1}{4}\)). \(\frac{3}{7}\)
A=\(\frac{7}{5}\)- \(\frac{4}{5}\).\(\frac{3}{7}\)
A=\(\frac{7}{5}\)-\(\frac{12}{35}\)
A=\(\frac{37}{35}\)
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\(1\dfrac{13}{15}.0,75-\left(\dfrac{8}{15}+25\%\right).\dfrac{24}{47}-3\dfrac{12}{13}:3\)
\(=\dfrac{28}{15}.\dfrac{3}{4}-\left(\dfrac{8}{15}+\dfrac{1}{4}\right).\dfrac{24}{47}-\dfrac{51}{13}:3\)
\(=\dfrac{7}{5}-\dfrac{47}{60}.\dfrac{24}{47}-\dfrac{17}{13}\)
\(=\dfrac{7}{5}-\dfrac{2}{5}-\dfrac{17}{13}\)
\(=1-\dfrac{17}{13}=-\dfrac{4}{13}\)
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a:\(=5-\dfrac{7}{39}\cdot\dfrac{13}{7}+\dfrac{2}{9}=5-1+\dfrac{2}{9}=4+\dfrac{2}{9}=\dfrac{38}{9}\)
b: \(=\dfrac{28}{15}:\dfrac{3}{4}-\left(\dfrac{11}{20}+\dfrac{5}{20}\right)\cdot\dfrac{3}{7}\)
\(=\dfrac{112}{45}-\dfrac{4}{5}\cdot\dfrac{3}{7}\)
\(=\dfrac{112}{45}-\dfrac{12}{35}=\dfrac{676}{315}\)
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\(1\frac{13}{15}.0,75-\left(\frac{104}{195}+25\%\right).\frac{24}{47}-3\frac{13}{12}:3\)
= \(\frac{28}{15}.\frac{3}{4}-\left(\frac{104}{195}+\frac{1}{4}\right).\frac{24}{47}-\frac{49}{12}.\frac{1}{3}\)
= \(\frac{4.3.7}{4.3.5}-\frac{47}{60}.\frac{24}{47}-\frac{49}{36}\)
= \(\frac{7}{5}-\frac{2}{5}-\frac{49}{36}\)
= \(1-\frac{49}{36}\)
= \(-\frac{13}{36}\)
Chúc bạn làm bài tốt
\(1\frac{13}{15}.0,75-\left(\frac{104}{195}+25\%\right).\frac{24}{27}-3\frac{13}{12}:3\)
=\(\frac{28}{15}.\frac{3}{4}-\left(\frac{8}{15}+\frac{1}{4}\right).\frac{24}{47}-\frac{49}{12}.\frac{1}{3}\)
=\(\frac{7}{5}-\frac{47}{60}.\frac{24}{47}-\frac{49}{36}\)
=\(\frac{7}{5}-\frac{2}{5}-\frac{49}{36}\)
=\(\frac{-13}{36}\)
=0,65
\(\dfrac{13}{15}\) x 0,75 = \(\dfrac{13}{15}\) x \(\dfrac{3}{4}\)
= \(\dfrac{39}{60}\)