a) Ta có: \(\sqrt{5x}-\dfrac{1}{5}\sqrt{245x}=\dfrac{-4}{5}\)
\(\Leftrightarrow\sqrt{5x}-\dfrac{7}{5}\sqrt{5x}=-\dfrac{4}{5}\)
\(\Leftrightarrow\dfrac{-2}{5}\sqrt{5x}=\dfrac{-4}{5}\)
\(\Leftrightarrow\sqrt{5x}=2\)
\(\Leftrightarrow5x=4\)
hay \(x=\dfrac{4}{5}\)
b) Ta có: \(5\sqrt{12x}-4\sqrt{3x}+2\sqrt{48x}=14\)
\(\Leftrightarrow10\sqrt{3x}-4\sqrt{3x}+8\sqrt{3x}=14\)
\(\Leftrightarrow3x=1\)
hay \(x=\dfrac{1}{3}\)
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