Question

TÌM X

\(X^3-X^2=12X\)

Answer 1

\(\Leftrightarrow x^3-x^2-12x=0\\ \Leftrightarrow x\left(x^2-x-12\right)=0\\ \Leftrightarrow x\left(4x^2-4x-48\right)=0\\ \Leftrightarrow x\left[\left(4x^2+12x\right)-\left(16x+48\right)\right]=0\\ \Leftrightarrow x\left[4x\left(x+3\right)-16\left(x+3\right)\right]=0\\ \Leftrightarrow x\left(4x-16\right)\left(x+3\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=0\\x=4\\x=-3\end{matrix}\right.\)