1) Ta có: \(\frac{-1}{3}x\left(1+x\right)+x\left(\frac{1}{3}x-2\right)=5\)
\(\Leftrightarrow\frac{-1}{3}x+\frac{-1}{3}x^2+\frac{1}{3}x^2-2x=5\)
\(\Leftrightarrow\frac{-7}{3}x=5\)
\(\Leftrightarrow x=5:\frac{-7}{3}=\frac{15}{-7}\)
Vậy: \(x=-\frac{15}{7}\)
2) Ta có: \(2x^2-7x+5=0\)
\(\Leftrightarrow2x^2-2x-5x+5=0\)
\(\Leftrightarrow2x\left(x-1\right)-5\left(x-1\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left(2x-5\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-1=0\\2x-5=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2\\2x=5\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2\\x=\frac{5}{2}\end{matrix}\right.\)
Vậy: \(x\in\left\{2;\frac{5}{2}\right\}\)
