\(x^3+3x^2+3x=0\\ \Leftrightarrow x\left(x^2+3x+3\right)=0\\ \Leftrightarrow x=0\left(x^2+3x+3=x^2+3x+\dfrac{9}{4}=\left(x+\dfrac{3}{2}\right)^2+\dfrac{3}{4}>0\right)\)
\(x^3+3x^2+3x=0\)
\(\Rightarrow x\left(x^2+3x+3\right)=0\)
Mà: \(x^2+3x+3>0\)
=> x = 0
\(x^3+3x^2+3x=0\)
\(\Leftrightarrow x\left(x^2+3x+3\right)=0\)
mà \(x^2+3x+3=\left(x+\dfrac{3}{2}\right)^2+\dfrac{3}{4}\ge\dfrac{3}{4}>0\forall x\)
\(\Rightarrow x=0\)
\(x^3+3x^2+3x=0\)
\(\Leftrightarrow x\left(x^2+3x+3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x^2+3x+3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x^2+2\cdot x\cdot\dfrac{3}{2}+\dfrac{9}{4}+\dfrac{3}{4}=0\end{matrix}\right.\)
\(\Leftrightarrow x=0\)
