`(x+2)(x-3)=0`
`to`\(\left[ \begin{array}{l}x+2=0\\x-3=0\end{array} \right.\)` <=>`\(\left[ \begin{array}{l}x=-2\\x=3\end{array} \right.\)
`tox={-2;3}`
`|x+6|=2x+9`
`to`\(\left[ \begin{array}{l}\text{+TH1: }x\geq 6\to x+6=2x+9\\\text{+TH2 : }x\leq6\to x+6=-2x-9\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x-2x=9-6\\x+2x=-9-6\end{array} \right.\) `<=>`\(\left[ \begin{array}{l}x=-3(TM)\\x=-5(KTM)\end{array} \right.\)
`->x=-3`
