Question

Answer 1

\(b,ĐKXĐ:5x\ge0\Leftrightarrow x\ge0\\ \left(\sqrt{5x}-1\right)\left(x^2+1\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}\sqrt{5x}-1=0\\x^2+1=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}\sqrt{5x}=1\\x^2=-1\left(vô.lí\right)\end{matrix}\right.\\ \Leftrightarrow5x=1\\ \Leftrightarrow x=\dfrac{1}{5}\left(tm\right)\)

\(c,\left(x-1\right)^3=\dfrac{1}{8}\\ \Leftrightarrow\left(x-1\right)^3=\left(\dfrac{1}{2}\right)^3\\ \Leftrightarrow x-1=\dfrac{1}{2}\\ \Leftrightarrow x=\dfrac{3}{2}\)