\(\Leftrightarrow\left(x+3\right)^2\cdot\left(x-3\right)^2-6\left(x+3\right)=0\)
\(\Leftrightarrow\left(x+3\right)\left[\left(x^2-9\right)\left(x-3\right)-6\right]=0\)
\(\Leftrightarrow\left(x+3\right)\left(x^3-3x^2-9x+21\right)=0\)
=>x+3=0
hay x=-3
\(\Leftrightarrow\left(x+3\right)^2\left(x-3\right)^2=6\left(x+3\right)\)
\(\Leftrightarrow\left(x+3\right)\left[\left(x+3\right)\left(x-3\right)^2-6\right]=0\)
Vì \(\left[\left(x+3\right)\left(x-3\right)^2-6\right]\ne0\)
\(\Rightarrow x+3=0\)
\(\Rightarrow x=-3\)
\(\Leftrightarrow\left(x^2-9\right)^2-6\left(x+3\right)=0\Leftrightarrow\left(x+3\right)\left[\left(x-3\right)^2\left(x+3\right)-6\right]=0\)
\(\Leftrightarrow\left(x+3\right)\left[\left(x^2-6x+9\right)\left(x+3\right)-6\right]=0\)
\(\Leftrightarrow\left(x+3\right)\left(x^3+3x^2-6x^2-18x+9x+27-6\right)=0\)
\(\Leftrightarrow\left(x+3\right)\left(x^3-3x^2-9x+21\right)=0\)
\(\Leftrightarrow x=-3;x\approx-2,8;3,9;1,89\)
