`|x+3|=2`
`<=>`\(\left[ \begin{array}{l}x+3=2\\x+3=-2\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=-1\\x=-5\end{array} \right.\)
`=>x=-1text( hoặc )x=-5`
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`7-5(x-2)=3+2(4-x)`
`<=>7-5x+10=3+24-2x`
`<=>17-5x=27-2x`
`<=>-5x+2x=27-17`
`<=>-3x=20`
`<=>x=-20/3`
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`(x^2-9)(x^2+1)=0`
`<=>`\(\left[ \begin{array}{l}x^2-9=0\\x^2+1=0\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x^2=9⇔\left[ \begin{array}{l}x=3\\x=-3\end{array} \right. \\x^2=-1(\text{vô lí})\end{array} \right.\)
`=>x=3text( hoặc )x=-3`
