Lời giải:
a)
\(8\sqrt{x}=x^2\Leftrightarrow 8\sqrt{x}=\sqrt{x^4}\)
\(\Leftrightarrow \sqrt{x^4}-8\sqrt{x}=0\)
\(\Leftrightarrow \sqrt{x}(\sqrt{x^3}-8)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}\sqrt{x}=0\\\sqrt{x^3}-8=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\\left(\sqrt{x}\right)^3=2^3\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\\sqrt{x}=2\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=4\end{matrix}\right.\) (đều thỏa mãn)
b)
Ta có: \(|5x-3|=|x-7|\)
\(\Leftrightarrow\left[{}\begin{matrix}5x-3=x-7\\5x-3=7-x\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}4x=-4\\6x=10\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-1\\x=\dfrac{5}{3}\end{matrix}\right.\)
