\(-x+\sqrt{x+1}+2\sqrt{x+2}=0\)
\(\Leftrightarrow-x+\left(\sqrt{x+1}\right)^2+2\left(\sqrt{x+2}\right)^2=0\)
\(\Leftrightarrow-x+x+1+2\left(x+2\right)=0\)
\(\Leftrightarrow-x+x+1+2x+4=0\)
\(\Leftrightarrow1+2x+4=0\)
\(\Rightarrow2x=-5\)
\(\Rightarrow x=-\dfrac{5}{2}\)
Vậy.............................................