a: Ta có: \(\sqrt{9x-9}-2\cdot\sqrt{\dfrac{x-1}{4}}=6\)
\(\Leftrightarrow3\sqrt{x-1}-\sqrt{x-1}=6\)
\(\Leftrightarrow2\sqrt{x-1}=6\)
\(\Leftrightarrow x-1=9\)
hay x=10
b: Ta có: \(\sqrt{4x^2+4x+1}=3\)
\(\Leftrightarrow\left|2x+1\right|=3\)
\(\Leftrightarrow\left[{}\begin{matrix}2x+1=3\\2x+1=-3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=2\\2x=-4\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1\\x=-2\end{matrix}\right.\)
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