\(\frac{1}{x-1}+\frac{2x^2-5}{x^3-1}=\frac{4}{x^2+x+1}\) ĐKXĐ : \(x^3-1\ne0\) <=> \(x^3\ne1\) <=> \(x\ne1\)
<=> \(\frac{x^2+x+1}{\left(x-1\right)\left(x^2+x+1\right)}+\frac{2x^2-5}{\left(x-1\right)\left(x^2+x+1\right)}=\frac{4\left(x-1\right)}{\left(x-1\right)\left(x^2+x+1\right)}\)
=> \(x^2+x+1+2x^2-5=4\left(x-1\right)\)
<=> \(3x^2+x-4=4x-4\)
<=> \(3x^2-3x=0\)
<=> 3x(x-1)=0
<=> \(\begin{matrix}3x=0\\x-1=0\end{matrix}< =>\begin{matrix}x=0\left(tm\right)\\x=1\left(ktm\right)\end{matrix}\)
vậy \(S=\left\{0\right\}\)