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19 tháng 3 2019
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: \(x\in\left\{3;-5\right\}\)
23 tháng 4 2019
a,\(\frac{4}{9}.\frac{2}{6}=\frac{4}{27}\)
b,\(1\frac{1}{3}.\left(0,5\right)+\left(\frac{8}{15}-\frac{19}{30}\right):\frac{6}{15}\)
=\(\frac{4}{3}.\frac{1}{2}+\left(\frac{16}{30}-\frac{19}{30}\right).\frac{15}{6}\)
=\(\frac{2}{3}+\frac{-1}{10}.\frac{15}{6}\)
=\(\frac{2}{3}+\frac{-1}{4}\)
=\(\frac{8}{12}+\frac{-3}{12}=\frac{5}{12}\)
bài2
a,\(\left(\frac{2}{7}.x+\frac{3}{7}\right):2\frac{1}{5}-\frac{3}{7}=1\)
=>\(\left(\frac{2}{7}.x+\frac{3}{7}\right):\frac{11}{5}=1+\frac{3}{7}=\frac{10}{7}\)
=>\(\frac{2}{7}.x+\frac{3}{7}=\frac{10}{7}.\frac{11}{5}\)
=>\(\frac{2}{7}.x+\frac{3}{7}=\frac{22}{7}\)
=>\(\frac{2}{7}.x=\frac{22}{7}-\frac{3}{7}=\frac{19}{7}\)
=>\(x=\frac{19}{7}:\frac{2}{7}=\frac{19}{7}.\frac{7}{2}=\frac{19}{2}\)
vậy x\(=\frac{19}{2}\)
0,5+2/3x=4/3-1/6
0,5+2/3x=7/6
2/3x=7/6-0,5
2/3x=2/3
x=2/3:2/3
x=1
Vậy x=1
\(\frac{4}{3}-\left(0,5+\frac{2}{3}x\right)=\frac{1}{6}\)
\(\Rightarrow\left(0,5+\frac{2}{3}x\right)=\frac{4}{3}-\frac{1}{6}\)
\(\Rightarrow\left(0,5+\frac{2}{3}x\right)=\frac{7}{6}\)
\(\Rightarrow\frac{2}{3}x=\frac{7}{6}-0,5\)
\(\Rightarrow\frac{2}{3}x=\frac{4}{6}\)
\(\Rightarrow\frac{2}{3}x=\frac{2}{3}\)
\(\Rightarrow x=\frac{2}{3}\div\frac{2}{3}\)
\(\Rightarrow x=\frac{2}{3}\times\frac{3}{2}\)
\(\Rightarrow x=1\)