\(\sqrt{x+5}=\sqrt{x}+1\)
\(\Leftrightarrow x+5=\left(\sqrt{x}+1\right)^2\)
\(\Leftrightarrow x+5=x+2\sqrt{x}+1\)
\(\Leftrightarrow x+5-x-2\sqrt{x}-1=0\)
\(\Leftrightarrow4-2\sqrt{x}=0\)
\(\Leftrightarrow2\left(2-\sqrt{x}\right)=0\)
\(\Leftrightarrow2-\sqrt{x}=0\)
\(\Leftrightarrow\sqrt{x}=2\)
\(\Leftrightarrow x=4\)