\(\left(x^4\right)^3=\dfrac{x^{18}}{x^7}\)
⇔ \(x^{12}=x^{11}\)
⇔ \(x^{12}-x^{11}=0\)
⇔ \(x^{11}.\left(x-1\right)=0\)
⇔ \(\left[{}\begin{matrix}x^{11}=0\\x-1=0\end{matrix}\right.\)
⇔ \(\left[{}\begin{matrix}x=0\\x=0+1=1\end{matrix}\right.\)
Vậy \(x\) ∈ \(\left\{0;1\right\}\)