$b)_{}$ $(x-2)(x^2+2x+4)=19_{}$
$⇔x^3-8=19_{}$
$⇔x^3=27_{}$
$⇔x^3=3^3_{}$
$⇔x=3_{}$
$Vậy_{}$ $x=3_{}$
$b)_{}$ $(x-1)^2-(2x+3)^2=0_{}$
$⇔x^2-2x+1-(4x^2+12x+9)=0_{}$
$⇔x^2-2x+1-4x^2-12x-9=0_{}$
$⇔-3x^2-14x-8=0_{}$
$⇔3x^2+14x+8=0_{}$
$⇔3x^2+12x+2x+8=0_{}$
$⇔3x.(x+4)+2.(x+4)=0_{}$
$⇔(x+4)(3x+2)=0_{}$
$⇔_{}$ \(\left[ \begin{array}{l}x+4=0\\3x+2=0\end{array} \right.\) $⇔_{}$ \(\left[ \begin{array}{l}x=-4\\x=-\frac{2}{3}\end{array} \right.\)
$Vậy_{}$ $x_{1}=-4;$ $x_{2}=$ $-\frac{2}{3}$
$c)_{}$ $(x-1)^3-x.(x-2)^2-(x-2)=0_{}$x^3-3x^2+3x-1-x.(x^2-4x+4)-x+2=0_{}$
$⇔x^3-3x^2+3x-1-x^3+4x^2-4x-x+2=0_{}$
$⇔x^2-2x+1=0_{}$
$⇔(x-1)^2=0_{}$
$⇔x-1=0_{}$
$⇔x=1_{}$
$Vậy_{}$ $x=1_{}$
