\(3x^2+1x-10=0\)
\(\Rightarrow3x^2+6x-5x-10=0\)
\(\Rightarrow\left(3x^2+6x\right)-\left(5x+10\right)=0\)
\(\Rightarrow3x.\left(x+2\right)-5.\left(x+2\right)=0\)
\(\Rightarrow\left(x+2\right).\left(3x-5\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x+2=0\\3x-5=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0-2\\3x=5\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=-2\\x=5:3\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=-2\\x=\frac{5}{3}\end{matrix}\right.\)
Vậy \(x\in\left\{-2;\frac{5}{3}\right\}.\)
Sao lại lấy 3 làm nhân tử chung được?
Chúc bạn học tốt!
