a)\(3x^2-6x=0\)
\(\Rightarrow3x\left(x-2\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}3x=0\\x-2=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=0\\x=2\end{matrix}\right.\)
b) \(5x\left(x-1\right)=x-1\)
\(\Rightarrow5x\left(x-1\right)-x+1=0\)
\(\Rightarrow5x\left(x-1\right)-1\left(x-1\right)=0\)
\(\Rightarrow\left(5x-1\right)\left(x-1\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{1}{5}\\x=1\end{matrix}\right.\)
c) \(2\left(x+5\right)-x^2-5x=0\)
\(\Rightarrow2\left(x+5\right)-x\left(x+5\right)=0\)
\(\Rightarrow\left(x-2\right)\left(x+5\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=2\\x=-5\end{matrix}\right.\)