\(\sqrt{x+9}=5-\sqrt{2x+4}\left(đk:4\ge x\ge-2\right)\Leftrightarrow\sqrt{x+9}+\sqrt{2x+4}=5\Leftrightarrow x+9+2x+4+2\sqrt{\left(x+9\right)\left(2x+4\right)}=25\Leftrightarrow12-3x=2\sqrt{\left(x+9\right)\left(2x+4\right)}\Leftrightarrow144-72x+9x^2=4\left(2x^2+22x+36\right)\Leftrightarrow x^2-160x=0\Leftrightarrow x\left(x-160\right)=0\)\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=160\end{matrix}\right.\)(0 thỏa đk, 160 không thỏa)\(\Leftrightarrow x=0\)
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