a) \(x\left(x^2-1\right)=0\)
\(\Rightarrow x\left(x-1\right)\left(x+1\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=0\\x=1\\x=-1\end{matrix}\right.\)
b) \(x\left(x^2+8\right)-3\left(x+8\right)=0\)
\(\Rightarrow x^3+5x-24=0\)
Rồi lấy máy tính nhấn nghiệm hộ.
a) \(x\left(x^2-1\right)=0\)
\(\Leftrightarrow x\left(x-1\right)\left(x+1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x-1=0\\x+1=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=1\\x=-1\end{matrix}\right.\)
Vậy........
b) \(x\left(x^2+8\right)-3\left(x+8\right)=0\)
\(\Leftrightarrow\left(x^3+8x\right)-\left(3x+24\right)=0\)
\(\Leftrightarrow x^3+8x-3x-24=0\)
\(\Leftrightarrow x^3+5x-24=0\)
\(\Leftrightarrow x=2,315872432\)
