\(x^2\left(x-3\right)-\left(x^2+5\right)+2x+5=0\)
\(\Leftrightarrow x^3-3x^2-x^2-5+2x+5=0\)
\(\Leftrightarrow x^3-4x^2+2x=0\)
\(\Leftrightarrow x\left(x^2-4x+2\right)=0\)
\(\Leftrightarrow x\left[\left(x^2-4x+4\right)-2\right]=0\)
\(\Leftrightarrow x\left(x-2-\sqrt{2}\right)\left(x-2+\sqrt{2}\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x-2-\sqrt{2}=0\\x-2+\sqrt{2}=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=2+\sqrt{2}\\x=2-\sqrt{2}\end{matrix}\right.\)
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