Question

\(\sqrt{3-5x}\)=2

 

Answer 1

đk x \(\le\dfrac{3}{5}\)

\(\left(\sqrt{3-5x}\right)^2=4\\ 3-5x=4\\ -5x=4-3\\ -5x=1\\ x=-\dfrac{1}{5}\left(thoaman\right)\)

Answer 2

\(\sqrt{3-5x}=2\) \(ĐK:x\le\dfrac{3}{5}\)

\(\Rightarrow\sqrt{\left(3-5x\right)^2}=2^2\)

\(\Rightarrow\left|3-5x\right|=4\)

\(\Rightarrow\left[{}\begin{matrix}3-5x=4\\5x-3=4\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}5x=-1\\5x=7\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=-\dfrac{1}{5}\left(thoaman\right)\\x=\dfrac{7}{5}\left(loại\right)\end{matrix}\right.\)