\(x^5-27+x^3-27x^2=0\)
\(< =>\left(x^5+x^3\right)-\left(27x^2+27\right)=0\)
\(< =>x^3\left(x^2+1\right)-27\left(x^2+1\right)=0\)
\(< =>\left(x^2+1\right)\left(x^3-27\right)=0\)
\(< =>\left[{}\begin{matrix}x^2+1=0\\x^3-27=0\end{matrix}\right.< =>\left[{}\begin{matrix}x^2=-1\\x^3=3^3\end{matrix}\right.\)
<=>\(\left[{}\begin{matrix}x-v\text{ô}-nghi\text{ệ}m\\x=3\end{matrix}\right.\)
S=\(\left\{R,3\right\}\)
