đkxđ:x>=-1
\(\sqrt{x+1}+\sqrt{x+9}=4\)
\(\Leftrightarrow\sqrt{x+1}=4-\sqrt{x+9}\)
\(\Leftrightarrow x+1=16-8\sqrt{x+9}+x+9\)
\(\Leftrightarrow8\sqrt{x+9}=24\)
\(\Leftrightarrow\sqrt{x+9}=3\)
\(\Leftrightarrow x+9=9\Leftrightarrow x=0\left(TM\right)\)
vậy x = 0