$(x.x+4x+3)(x.x+6x+8)=0$
$⇒[(x²+x)+(3x+3)][(x²+2x)+(4x+8)]=0$
$⇒[x(x+1)+3(x+1)][x(x+2)+4(x+2)]=0$
$⇒(x+1)(x+3)(x+2)(x+4)=0$
⇒\(\left[ \begin{array}{l}x+1=0\\x+3=0\\x+2=0\\x+4=0\end{array} \right.\)
⇒\(\left[ \begin{array}{l}x=-1\\x=-3\\x=-2\\x=-4\end{array} \right.\)
Chúc bạn học tốt nhé! ^^