ĐKXĐ: \(x>0\)
a.
\(log^2_{0.2}x-5log_{0.2}x+6=0\)
\(\Leftrightarrow\left(log_{0.2}x-2\right)\left(log_{0.2}x-3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}log_{0.2}x=2\\log_{0.2}x=3\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{1}{25}\\x=\dfrac{1}{125}\end{matrix}\right.\)
b.
\(log_{0.2}^2x-5log_{0.2}x+6>0\)
\(\Leftrightarrow\left[{}\begin{matrix}log_{0.2}x>3\\log_{0.2}x< 2\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}0< x< \dfrac{1}{125}\\x>\dfrac{1}{25}\end{matrix}\right.\)
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