\(28x^{2017}-4x^{2018}=0\)
\(\Rightarrow4x^{2017}\left(7-x\right)=0\)
\(\Rightarrow\orbr{\begin{cases}4x^{2017}=0\\7-x=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=0\\x=7\end{cases}}\)
\(28x^{2017}-4x^{2018}=0\)
\(\Leftrightarrow4x^{2017}.\left(7-x\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}4x^{2017}=0\\7-x=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=0\\x=7\end{cases}}}\)