Ta có :
\(\sqrt{x+2\sqrt{x-1}}=5\)
\(\Leftrightarrow x+2\sqrt{x-1}=25\)
\(\Leftrightarrow x-1+2\sqrt{x-1}+1=25\)
\(\Leftrightarrow\left(\sqrt{x-1}+1\right)^2=25\)
\(\Leftrightarrow\left[{}\begin{matrix}\sqrt{x-1}+1=5\\\sqrt{x-1}+1=-5\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}\sqrt{x-1}=4\\\sqrt{x-1}=-6\left(loại\right)\end{matrix}\right.\)
\(\Leftrightarrow x-1=16\Leftrightarrow x=17\)
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