( 3x + 3/5 ) . ( /x/ - 1/4 ) = 0
Tìm x
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a: Ta có: \(\left(x-\dfrac{2}{5}\right)\left(x+\dfrac{2}{7}\right)>0\)
\(\Leftrightarrow\left[{}\begin{matrix}x>\dfrac{2}{5}\\x< -\dfrac{2}{7}\end{matrix}\right.\)
\(\dfrac{1}{3}x+\dfrac{2}{3}\left(x-1\right)=0\\ \dfrac{1}{3}x+\dfrac{2}{3}x-\dfrac{2}{3}=0\\ x=\dfrac{2}{3}\)
\(\Leftrightarrow2x^2-11x+5-2x^2+10x=25\Leftrightarrow-x=20\Leftrightarrow x=-20\)
Ta có: \(\left(x-2\right)^3-x\left(x-1\right)\left(x+1\right)+x\left(7x-6\right)=0\)
\(\Leftrightarrow x^3-6x^2+12x-8-x^3+x+7x^2-6x=0\)
\(\Leftrightarrow x^2+7x-8=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-8\\x=1\end{matrix}\right.\)
\(\Leftrightarrow\left(x-2021\right)\left(x-5\right)-\left(x-2021\right)=0\\ \Leftrightarrow\left(x-2021\right)\left(x-6\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=2021\\x=6\end{matrix}\right.\)
\(\left(3x+\frac{3}{5}\right).\left(\left|x\right|-\frac{1}{4}\right)=0\)
\(\Rightarrow\orbr{\begin{cases}3x+\frac{3}{5}=0\\\left|x\right|-\frac{1}{4}=0\end{cases}}\Rightarrow\orbr{\begin{cases}3x=\frac{3}{5}\\\left|x\right|-\frac{1}{4}\end{cases}}\Rightarrow\orbr{\begin{cases}x = \frac{1}{5}\\x∈ \left\{\frac{-1}{4};\frac{1}{4}\right\}\end{cases}}\)