$(2x+10)(4x+8)=0$
$⇔$ \(\left[ \begin{array}{l}2x+10=0\\4x+8=0\end{array} \right.\)
$⇔$ \(\left[ \begin{array}{l}2x=-10\\4x=-8\end{array} \right.\)
$⇔$ \(\left[ \begin{array}{l}x=-5.\\x=-2.\end{array} \right.\)
Vậy...
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$2,5x-3+5,1x+3,8=0$
$⇔2,5x+5,1x=0+3-3,8$
$⇔7,6x=−0,8$
$⇔x=\frac{-2}{19}$
Vậy...
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$(x+1)−(2x+1)=9−x$
$⇔x+1−2x−1=9−x$
$⇔x−2x+x=9−1+1$
$⇔0x=9$
$⇔0x=9.$ (vô lí)
Vậy $x∈∅$
