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\(\left(\dfrac{-2}{3}\right).0,75+\dfrac{1}{\dfrac{2}{3}}:\left(\dfrac{-4}{9}\right)+\left(\dfrac{-1}{2}\right)\)
\(=\left(\dfrac{-2}{3}\right).\dfrac{3}{4}+\dfrac{5}{3}:\left(\dfrac{-8}{18}\right)+\left(\dfrac{-9}{18}\right)\)
\(=\dfrac{-1}{2}+\dfrac{5}{3}.\dfrac{-18}{8}+\dfrac{-9}{18}\)
\(=\dfrac{-1}{2}+\dfrac{-15}{4}+\dfrac{-9}{18}\)
\(=\dfrac{-72}{144}+\dfrac{-540}{144}+\dfrac{-72}{144}\)
\(=\dfrac{-684}{144}\)
\(=\dfrac{-19}{4}.\)
\(1\frac{3}{8}+\frac{1}{8}:\left(0,75-\frac{1}{2}\right)-25\%.\frac{1}{2}\)
=\(\frac{11}{8}+\frac{1}{8}:\frac{1}{4}-\frac{1}{4}.\frac{1}{2}\)
=\(\frac{11}{8}+\frac{1}{2}-\frac{1}{8}\)
=\(\frac{5}{4}+\frac{1}{2}\)
=\(\frac{7}{4}\)
lam dung 100% Lấy máy tính, bấn theo đề bài => ra kết quả.
1, \(\dfrac{-3}{5}:\dfrac{7}{5}-\dfrac{3}{5}:\dfrac{7}{5}+2\dfrac{3}{5}\)
\(=\left(\dfrac{-3}{5}-\dfrac{3}{5}\right):\dfrac{7}{5}+\dfrac{13}{5}\)
\(=\dfrac{-6}{5}:\dfrac{7}{5}+\dfrac{13}{5}\)
\(=\dfrac{-6}{7}+\dfrac{13}{5}\\ =\dfrac{61}{35}\)
2, \(0,75-\left(2\dfrac{1}{3}+0,75\right)+3^2\cdot\left(-\dfrac{1}{9}\right)\)
\(=0,75-\dfrac{37}{12}+9\cdot\left(-\dfrac{1}{9}\right)\)
\(=-\dfrac{7}{3}+\left(-1\right)\\ -\dfrac{10}{3}\)
a) \(-\frac{7}{2}:\left(3-x\right)-0,75=\frac{1}{4}\)
\(\Leftrightarrow\frac{-7}{2\left(3-x\right)}=\frac{1}{4}+0,75=0,25+0,75=1\)
\(\Leftrightarrow2\left(3-x\right)=-7\)
\(\Leftrightarrow3-x=-\frac{7}{2}\)
\(\Leftrightarrow x=3+\frac{7}{2}\)
\(\Leftrightarrow x=\frac{13}{2}\)
b) \(\left|2x-\frac{4}{3}\right|-1\frac{1}{3}=-\frac{8}{9}\)
\(\Leftrightarrow\left|2x-\frac{4}{3}\right|=\frac{4}{3}-\frac{8}{9}=\frac{4}{9}\)
\(\Leftrightarrow\orbr{\begin{cases}2x-\frac{4}{3}=\frac{4}{9}\\2x-\frac{4}{3}=-\frac{4}{9}\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}2x=\frac{4}{3}+\frac{4}{9}=\frac{16}{9}\\2x=\frac{4}{3}-\frac{4}{9}=\frac{8}{9}\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=\frac{8}{9}\\x=\frac{4}{9}\end{cases}}\)
\(=0.75-\dfrac{7}{3}-0.75+9\cdot\left(-\dfrac{1}{9}\right)=-\dfrac{7}{3}-1=-\dfrac{10}{3}\)
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