$\sqrt{x+5+4\sqrt{x+1}}=x+3$
$\sqrt{x+1+2.2\sqrt{x+1}+2^2}=x+3$
$\sqrt{(\sqrt{x+1}+2)^2}=x+3$
$|\sqrt{x+1}+2|=x+3$
\(\left[ \begin{array}{l}\sqrt{x+1}+2=x+3\\\sqrt{x+1}+2=-x-2\end{array} \right.\)
\(\left[ \begin{array}{l}\sqrt{x+1}=x+1\\\sqrt{x+1}=-x-4\end{array} \right.\)
\(\left[ \begin{array}{l}x+1=(x+1)^2\\x+1=(x+4)^2\end{array} \right.\)
\(\left[ \begin{array}{l}x+1=x^2+2x+1\\x+1=x^2+8x+16\end{array} \right.\) (đến đây giải như bình thường)
