a, \(2x-6=0\)
\(2\left(x-3\right)=0\)
\(\Rightarrow x=3\)
b, \(\left(x+2\right)\left(3x-12\right)=0\)
\(3\left(x+2\right)\left(x-4\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=-2\\x=4\end{matrix}\right.\)
câu 11 :
\(a,2x-6=0\\ 2x=0+5\\ 2x=6\\ x=6:2\\ x=3\\ b,\left(x+2\right)\left(3x-12\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x+2=0\\3x-12=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=-2\\3x=12\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=-2\\x=4\end{matrix}\right.\)
c, \(\dfrac{5x+4}{x^2+2x}+\dfrac{3x}{x+2}=\dfrac{2}{x}\left(đk:x\ne0;-2\right)\)
\(\dfrac{5x+4+3x^2-2\left(x+2\right)}{x^2+2x}=0\)
\(5x+4+3x^2-2x-4=0\)
\(3x^2+3x=0\)
\(3x\left(x+1\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=0\\x=-1\end{matrix}\right.\)
