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![](https://rs.olm.vn/images/avt/0.png?1311)
\(\left(\dfrac{x}{2}+3\right)\left(5-6x\right)+\left(12x-2\right)\left(\dfrac{x}{4}+3\right)=0\)
\(\dfrac{5x}{2}-3x^2+15-18x+3x^2+36x-\dfrac{x}{2}-6=0\)
\(\dfrac{5x}{2}-\dfrac{x}{2}+18x+9=0\)
\(20x+9=0\)
\(x=\dfrac{-9}{20}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\Leftrightarrow-x^2-2x-1=3x-x^2+2x\)
=>-2x-1=5x
=>-7x=1
hay x=-1/7
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\left(2x+3\right)^2+\left(x-1\right)\left(x+1\right)=5\left(x+2\right)^2-\left(x-5\right)\left(x+1\right)+\left(x+4\right)^2\)
\(\Leftrightarrow\left(2x+3\right)^2-\left(x+4\right)^2+\left(x-1\right)\left(x+1\right)+\left(x-5\right)\left(x+1\right)=5\left(x^2+4x+4\right)\)
\(\Leftrightarrow\left(2x+3+x+4\right)\left(2x+3-x-4\right)+\left(x+1\right)\left(x-1+x-5\right)=5x^2+20x+20\)
\(\Leftrightarrow\left(3x+7\right)\left(x-1\right)+\left(x+1\right)\left(2x-6\right)=5x^2+20x+20\)
\(\Leftrightarrow3x^2-3x+7x-7+2x^2-6x+2x-6=5x^2+20x+20\)
\(\Leftrightarrow5x^2-13-5x^2-20=20x\)
\(\Leftrightarrow-33=20x\)
\(\Leftrightarrow x=\dfrac{-33}{20}\)
\(\Rightarrow S=\left\{\dfrac{-33}{20}\right\}\)
đề bài là tìm x à bạn? đề có cho điều kiện ko vậy ạ? (ví dụ như x nguyên?)
\(\left(x-1\right)^3+\left(x^3-8\right).3x.\left(x-1\right)=0\)
\(\Leftrightarrow\left(x-1\right).\left[\left(x-1\right)^2+\left(x^3-8\right).3x\right]=0\)
TH1: \(x-1=0\Leftrightarrow x=1\)
TH2: \(\left(x-1\right)^2+\left(x^3-8\right).3x=0\)
\(\Rightarrow\left[{}\begin{matrix}\left(x-1\right)^2=0\\\left(x^3-8\right).3x=0\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}x=1\\\left\{{}\begin{matrix}x^3-8=0\\3x=0\end{matrix}\right.\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1\\\left\{{}\begin{matrix}x=2\\x=0\end{matrix}\right.\end{matrix}\right.\)
Vậy \(x\in\left\{0;1;2\right\}\)