\(ab.aba=abab\Leftrightarrow ababa=abab\Leftrightarrow ababa-abab=0\)
\(\Leftrightarrow abab\left(a-1\right)=0\Leftrightarrow\left\{{}\begin{matrix}abab=0\\a-1=0\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}a=1\\bb=0\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}a=1\\b=0\end{matrix}\right.\)
vậy \(a=1;b=0\)
