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Bài 2:
a) \(\frac{4}{9}+x=\frac{-5}{3}\)
\(\Leftrightarrow x=\frac{-5}{3}-\frac{4}{9}\)
\(\Leftrightarrow x=\frac{-15}{9}-\frac{4}{9}\)\(=\frac{-19}{9}\)
Vậy: \(x=\frac{-19}{9}\)
b) \(2,4:\left(\frac{1}{2}.x-\frac{3}{4}\right)=\frac{3}{10}\)
\(\Leftrightarrow\frac{24}{10}:\left(\frac{1}{2}x-\frac{3}{4}\right)=\frac{3}{10}\)
\(\Leftrightarrow\frac{1}{2}x-\frac{3}{4}=\frac{24}{10}:\frac{3}{10}=\frac{24}{10}.\frac{10}{3}\)\(=8\)
\(\Leftrightarrow\frac{1}{2}x=8+\frac{3}{4}=\frac{35}{4}\)
\(\Leftrightarrow x=\frac{35}{4}:\frac{1}{2}=\frac{35}{4}.2=\frac{35}{2}\)
c) \(\frac{x+1}{-8}=\frac{-2}{x+1}\)
\(\Rightarrow\left(x+1\right).\left(x+1\right)=\left(-2\right).\left(-8\right)\)
\(\Leftrightarrow\left(x+1\right)^2=16=4^2=\left(-4\right)^2\)
\(\Rightarrow\left[{}\begin{matrix}x+1=4\\x+1=-4\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-5\end{matrix}\right.\)
Vậy: \(x\in\left\{3;-5\right\}\)
đặt
\(M=\frac{0,8:\left(\frac{4}{5}.1,25\right)}{0,64-\frac{1}{25}}=\frac{\frac{4}{5}.1}{\frac{16}{25}-\frac{1}{25}}=\frac{\frac{4}{5}}{\frac{3}{5}}=\frac{4}{3}\)
\(N=\frac{\left(1,08-\frac{2}{25}\right):\frac{4}{7}}{\left(6\frac{5}{9}-3\frac{1}{4}\right).2\frac{2}{17}}=\frac{\left(\frac{27}{25}-\frac{2}{25}\right):\frac{4}{7}}{\left(\frac{59}{9}-\frac{13}{4}\right).\frac{36}{17}}=\frac{1:\frac{4}{7}}{7}=\frac{1}{4}\)
\(=>M+N=\frac{3}{4}+\frac{1}{4}=1\)
\(\frac{1-0,5.\left(3,84-2,4\right)\div0,8}{\frac{4}{5}-\left(1\frac{1}{3}-2\frac{1}{6}\right)-1,5}\)
\(=\frac{0,5.1,44\div0,8}{\frac{2}{15}}\)
\(=\frac{\frac{9}{10}}{\frac{2}{15}}=\frac{27}{4}=6,75\)